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Mechanical engineering and 
machine shop practice 

Stanley Holmes Moore 



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MECHANICAL ENGINEERING 

AND 

MACHINE SHOP PRACTICE 



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"^0 9^ mitt 

WHOSE ASSISTANCE IN THE PREPARATION 

OF THE MANUSCRIPT HAS BEEN INVALUABLE, 

I DEDICATE THIS BOOK 



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MECHANICAL ENGINEERING 

AND 

MACHINE SHOP PRACTICE 



BY 

STANLEY H? MOORE 

Member or Associatt Am. Soc. Mech. Engrs^ Am. Inst. Elect. Engrs., Am. Asso. 

Adv. Sc, Am. Chem.Soc., Cen. Asso. Se. &* Math., Soe. Pro. 

Emg. Edu., Nai. Geog. Soc, Nat. Edu. Asso.^ 

Engineer^ Club, FratMin Institute 



1908 
HILL PUBLISHING COMPANY 

505 PEARL STREET, NEW YORK 

6 BOUVERIE STREET, LONDON. E.G. 
American Machinist — Poxver — The Engineering and Mining Journal 



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Copyright, 1908, Bt the Hill Publishing CoiiPANr 

DITESEO AT STATIONERS* HALL 



JJI rights rtstrved 



The Hill Publishing Company^ New rork, U,S,A, 



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PREFACE 









1. The book deals with modem machine shop practice and 
its correlative mechanical engineering and is written primarily 
as a text for the student and apprentice. 

2. The importance, and even necessity, of a limited knowledge 
, of Materials, Processes, Mechanics, Power Generation and Trans- 
mission, Electricity and Motor Drives, to any who have to do 
with machine shop practice, is obvious; and for this reason, 

v3 chapters containing much new matter on all these subjects have 

been incorporated in this work. 

3. While its description of tools and processes is elementary 
enough and was written for students, it contains the data of 
original investigations and much matter of special interest to 
the technical man. 

4. We have had and continue to have technical books from 
the theorist's, layman's and teacher's point of view, but the 
need of such works from the view-point of the student, apprentice 
and workman has long been apparent. By far the larger number 
of the paragraphs were written to answer actual questions that 

VD were asked by students and apprentices during their instruction 

in machine shop work. 

5. Its descriptions of processes were written with the fol- 
lowing paragraph from the Manual Training Magazine ever in 
mind. *'If the college instructor wishes to produce a book of 
value to the manual training teacher, let him make a clear, 
scholarly description of tools and the best methods of using 
them, without special reference to his own particular course of 
study (which is pretty sure not to be acceptable to other in- 
structors in his own grade of work, not to mention those of lower 
grades)." 

6. The "Characteristic Operations" and the "Order of Oper- 
ations" for the various machines and processes are general in 
character and yet specific enough for any one, able to read, to 
get the results desired. 






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vi PREFACE 

7. "If there is any one weakness common to all technical 
texts it is their faulty and meager index." An original and 
novel feature of the Table of Contents enables the reader, by 
means of the number after the subject, to tell at a glance the 
chapter, the classification and the section where the informa- 
tion may be found. Such a system of indexing necessitates and 
secures a full and logical treatment, not only of the author's 
specialties, but of the entire contents of the book. The illustra- 
tions are similarly indexed. 

8. The information contained has gone through a process of 
selection and revision for a period of three years and the entire 
contents have been submitted to a few engineers and educators 
for criticism and revision. 

9. Several portions have already been published in such repu- 
table periodicals as the American Machinist, Power, Machinery, 
etc. One portion, Fits and Fitting, was delivered as a paper 
before the American Society of Mechanical Engineers; this 
paper was afterwards copied by a few European editors. 

10. No apology is tendered for the use of half-tones, cuts, 
tables, etc., from the catalogs of the various manufacturers. 
Their function is obvious, as much material is available from no 
other source. The information which these catalogs often con- 
tain, the ability of the engineers who prepared them, and the 
skill of the artists who illustrated them, is unsurpassed. 

The author desires to acknowledge his indebtedness to, and 
to thank all, — the publishers, manufacturers and collaborators, 
— for their assistance and courtesy tendered in the preparation 
of the work. 



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CONTENTS^ 

CHAPTER I. INTRODUCTION AND EQUIPMENT 

PAGE 

Introduction 1 

Foreword, 111; Character of Instruction. 112; Shop Ethics, 113; 
Carefulness in the Shop, 114; Care of Self, 115; Care of Machine, 
116; Tools and Work, 117. 

Shop Equipment and Regulation 6 

Machine Tool Equipment for Shop or Laboratorv, 121; The Tool- 
room, 122; The Check System, 123; The Record System, 124; Tool- 
room Rules for School Shops, 125. 

CHAPTER II. MATERIALS 

Iron, Metallurgy 11 

Ores and Their Reduction, 211; Graphical Illustration of the 
Metallurgy of Iron, 212; Metallurgical Notes, 213; Influence of 
Carbon, Manganese and Phosphorus, 214; Influence of Chromium 
and Nickel, 215; Influence of Silicon and Sulphur, 216; Influence 
of Tungsten, Molybdenum and Vanadium, 217; Influence of Alu- 
minum, Cobalt, Tm and Titanium, 218; Graph and Table of Physical 
Properties, 219. 

Pig Iron 20 

Classification of Commercial Pig Irons, 221: Bessemer, 222; Foun- 
dry, 223; Charcoal, 224; Basic, 225; Ferro-Silicon, 226; Gray Foree, 
227. 

Cast Iron 21 

Classification and Analyses of Standard Cast Irons, 231 : Malleable 
Cast Iron, 232; Annealed Castings, 233; Case-hardened Castings, 
234; Uses, Adaptability and Comparison with Wrought Iron and 
Steel, 235. 

Wrought Iron 24 

Manufacture, Norway, Charcoal, Puddled and Fagot Irons, 241; 
Properties, 242; Conmiercial Designation, 243; Working, 244. 

Steel, Commercial Steels and Their Products 25 

Classification, 251; Converted or Cemented, 252; Blister, 253; 
German, 254; Single and Double Shear. 255; Crucible Cast, 256; 
Bessemer, 257; Open Hearth and Puddled, 258; Tool or Carbon 
Steels, 259. 

Steel, Alloy and High Speed 28 

Chrome Steel, 261; Nickel Steel, 262; Nickel-Chrome Steel, 263; 
Manganese Steel, 264; Silicon Steel, 265; Tungsten or Mushet 
Steel, 266; Vanadium and Chrome Vanadium Steels, 267; Aluminum, 

1 Figures in contents refer to sections, not pages. Interpreting 260 we have, 2 — Chapter 
2; 6 — Classification 6 of Chapter 2; -> Section of 6th classification of Chapter 2: or in 
the instance of 1735, 17 « Chapter 17, Power Generation; 3 =■ Classifications, Hydraulic 
Motors; 5 *- Section 5, Reaction Wheels. 

vii 



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viii CONTENTS 

PAGE 

Ck)balt, Tin, Titanium and Other Steels, 268; High-Speed Cutting 
Tool Alloys, 269. 

Steel, Manipulation 35 

Steel Castings, 271; Structure, 272; Treatment, 273; Working, 274; 
Theory of Hardening, 275; Hardening and Tempering, 276; Table 
of Tempering Data, 277; Taylor-White Treatment of Tool Steels, 
278. 

Alloys, Bronzes, Brasses, etc 42 

Properties and Characteristics, 281; Bronzes, Copper-Tin Alloys, 
282; Phosphor Bronze, 283; Brasses, Copp?r-Zinc Alloys, 284; 
Copper-Tin-Zinc Alloys, 285; Lead, Use in Alloys, 286; Composi- 
tion of 26 Ordinary Commercial Alloys, 287; Telephone and Tele- 
graph Wire Alloys, 288. 

Alloys, Solders, Bearing Metal and Other Well known Alloys. 46 
Common Solder, Common Pewter, Gold Solder, Silver Solder and 
German Silver Solder, 291 ; Bearing Metal Alloys, — Babbit Metal, 
292; Composition of 24 Bearing Metal Alloys, 293; (iurlcy's Bronze, 
294; German Silver, 295; Aluminum Bronze, 296; Manganese 
Bronze, 297; Pewter and Type Metal, 298; Fusible Alloys, 299. 

CHAPTER in. FRICTION, LUBRICANTS AND LUBRICATION 

Fricfion and Ix>8t Work 50 

Friction, 311; Friction Reduction, 312; laws of Friction, 313; 
Coefficient of Friction, 314; Solid Friction, 315; Fluid Friction, 316. 

Lubricants in General 53 

The Function of Lubricants, 321; The Selection of Lubricants, 322. 

Oil Compounds and Adulterations 53 

Composition of Oils, 331; Vegetable Oils, 332; Animal Oils, 333; 
Paraffine, 334; Wool Fat, 335; Objectionable Features, 336. 

Lubricating Oii-h 54 

Qualifications of a Good Lubricant, 341; Oil Tests, 342; Density of 
Gravity Test, 343; Viscosity or Fluidity Test, 344; Flash or Fire 
Test, 345; Acidity Test, 346; Cold Test, 347; Oil Ins{>ection, 348; 
Volatile Oils, 349. 

Oil Specifications 57 

Table of Chemical and Physical Properties of 12 Ordinary Lubri- 
cating Oils, 351 ; Lubricant Friction, 352; Lubricant Application, 353. 

Solid Lubricants 59 

Use of Solid Lubricants, 361; Graphite, 362; Talc, 363. 

Heat-dissipating Lubricants 60 

Twofold Action of Heat-dissipating Lubricants, 371; Heat-dissipat- 
ing Mixtures, 372; Dry Cuts, 373. 

CHAPTER IV. CUTTING TOOI^ 

Discussion 61 

Governing Conditions, 411; Keenness of the Tool, 412; Strength 
and Durability of the Cutting Edge, 413; Relative Positions of 
the Tool and Work, 414; Shape of the Tool and the Material to be 
Cut, 415. 

Feeds and Speeds 62 

The Surfaces of Metals and the Character of the Chip, 421; General 
Rules Relative to F(*t»ds and Specnis, 422; Remarks Concerning the 
Author's Investigations, 423; Author's Res(»arch — Ordinary Low- 
speed Tool Steels, 424; Alwtract of Professor Nicholson's Investiga- 



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CONTENTS ix 

PAGE 

tions, 425; Abstract of President Taylor's Investigations, 426; Tests 
of High-speed Tool Steels on Cast Iron, 427; Revolutions for Given 
Diameters and Cutting Speeds, 428; Examples of Recent Practice 
with High-speed Tool Steels, 429. 

Hand Tools, Grinding and Use 93 

Chisels, 431; Gravers, 432; Scrapers, 433. 

Lathe Tools 97 

The Diamond Point Tool, 441; The Round-nose Roughing Tool, 
442; The Side Tool, 443; The Parting or Cutting-off Tool, 444; 
The Boring Tool, 445; The Bull-nose Tool, 446; The Threading 
Tool, U. S. Std., 447; The Finishing Tool, 448; The Brass-working 
Tool, 449. 

Planer Tools 100 

Discussion and Theory, 451; The Roughing Planer Tool, 452; The 
Diamond Point Planer Tool, 453; The Straight-edge Side Tool, 
(Planer) 454; SlotterTools, 455; Shapes and Grinding of 25 Straight- 
faced Planer Tools, 456. 

Tool Holders with Self-hardening Steel Cutters .... 103 

Lathe Tools, 461; Planer Tools, 462. 

CHAPTER V. MEASURING AND SMALL TOOLS 

Standards OP Measurement 105 

Historical Statement, 511. 

Direct Measuring Tools 105 

Rules, 521; The Try Square, 522; The Micrometer Caliper, 523; 
The Micrometer Caliper Square, 524; The Vernier and Its use, 525* 
The Vernier Calipers, 526; The Straight-edg(^ 527; The Bevel 
Protractor, 528; Tables, Table of Tapers and Angles, Table of 
Angles of Geometrical Figures, 529. 

Gages 117 

Classification, 531. 

Dimensional Gages 117 

Test and Reference Gages, 541; Standard Cylindrical Gages, 542; 
Standard Calip>er Gages, 543; Limit Gages, 544. 

Numbered Gages 120 

Criticism, 551 ; The United States Standard Gagn, 552; The American 
or Brown & Shaipe Gage, 553; The Birmingham or Stubs' Wire 
Gage, 554; The Washburn & Moen Mfg. Go's. Gage, 555; The 
American Twist Drill Gage, 556; The American Screw Gage and 
Others, 557; Comparison of Wire, Sheet Metal and other Gages, 558. 

Small Tools — Various Gages 124 

The Screw Pitch Gage, 561 ; The Center Gage, 562; The Depth Gage, 
563; The Universal Surface Gage, 564. 

Small Tools, Ordinary Kit 127 

Arbors or Mandrels, 571; Reamers, 572; Calipers, 573; Dividers, 
574; Scribers, 575; Center Punches, 576; Wrenches, 577. 

CHAPTER VI. SCREW AND PIN DATA 

Screw Parts 135 

Nomenclature, 611; Pitch, 612; Lead, 613; Threads per Inch, 614; 

Turns to an Inch, 615. 
Standard Taps and Dies 136 

Standard Taps, 621; Machine Screw Taps, 622; Dies or Screw 

Plates, 623; Standard Pipe Taps and Dies, 624. 



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X CONTENTS 

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Screws 138 

Machine Screws, 631; Cap Screws, 632; Set Screws, 633; Coach or 
Lag Screws, 634; Hanger Screws, 635. 

BoLTB AND Studs 142 

Machine Bolts, 641; Coupling Bolts, 642; Carriage Bolts, 643; 
Stove Bolts, 644; Studs, 645. 

Nuts, Rivets, Coiters, etc 145 

Nuts, 651; Rivets, 652; Cotters, 653; Washers, 654; Burrs, 655; 
Tumbuckles, 656. 

Pin Data 147 

Dowel and Taper Pins, 661. 

Tabulated Bolt and Thread Data 148 

U. S. Standard Thread, Bolt and Nut Data, 671; Tap and Thread 
Data for Machine Screws, 672; Standard Dimensions of Wrou^t- 
iron Welded Pipe, 673; Table of Decimal Equivalents of an Inch, 
674; Standard Set and Cap Screws, 675; Standard Machine Screw 
Proportions and Other Data, 676. 

CHAPTER VII. BENCH AND VISE WORK 

Preliminary Process — Laying Out 161 

Laying Out Rectilinear Work, 711; Laying Out Cylindrical Work, 

712; Laying Out DriU Work, 713. 
Hammering and Sawing 162 

Hammering and Peening, 721; Hack Sawing, 722. 
Threading and Tapping 163 

Threading, 731; Tapping, 732; Aligning the Tap, 733; Depth of 

Tapped Holes, 734. 
Chipping 165 

Chipping and Its Applications, 741; Pneumatic Hammers, 742; 

The Chisel, 743; The Work, 744; The Cut, 745; Chipping Grooves, 

746. 
Filing and Files 168 

Application and Practice, 751; The Toob, 752; Care of Files, 753; 

Cross Filing, 754; Diagonal Filing, 755; Draw Filing, 756; Files 

and Their ^aracteristics, 757; File Table, Shapes, Cuts, Uses, etc., 

758. 
Scraping 171 

Scraping a Plane Surface, 761; Scraping in the Lathe, 762. 
Keys, Keyfittino and Broaching 173 

Kev Nomenclature, 771; Key Fitting, 772; Key Way Cutting, 773; 

Table of Standard Key Seats, 774; Broaching or Drifting, 775. 
Fits and Fitting 176 

Investigation, 781; Fitting Processes, 782; Forcing Fits, 783; 

Foreing Fit Pressures, 784; Shrinking Fite, 785; Driving Fits, 786; 

Running Fits, 787; Limits for Limit Gages, 788; Tabulated Data 

Relative to Fits and Fitting, 789. 

CHAPTER VIII. TURNING 

Turning Machines 1^ 

Lathes, 811; The Tool-maker's Lathe, 812; The Gap Lathe, 813; 
The Axle Lathe, 814; The Wheel Lathe, 815; The Turret Lathe, 
816; The Pulley Lathe, 817; The Crank Shaft Lathe, 817i; The 
Bench or Precision Lathe, 818; The Speed or Hand Lathe, 819. 



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CX)NTENTS xi 

PAGE 

Engine Lathe 193 

Description, 821; Characteristic Operations, 822. 

Preparatory Processes 201 

Centering, 831; Drilling and Countersinking, 832. 

Straight Turning 202 

Manipulation, 841; Order of Operations, 842. 

Finishing Processes 204 

Filing, 851; Scraping, 852; Polishing, 853. 

Taper Turning 205 

Methods of Turning Tapers, 861; Brown & Sharpe and Morse 
Tapers, 862; Rule for Set Over, 863; Theoretical Height of Tool, 864. 

Screw Cutting 208 

The Threading Tool, 871; Change Gearing, 872; Simple Gearing — 
Rule, 873; Compound Gearing, 874; Process and Manipulation, 875; 
Order of Operations for Screw Cutting, 876; Notes on Screw Cut- 
ting, 877. 

Ordinary Thread Proportions 215 

The U. S. Standard Thread, 881; The Square Thread, 882; The 
eO-Deeree V Thread, 883; The Brown & Sharpe 29-Degree Worm 
Thread, 884; The 29-Degree Screw Thread, Acme Standard, 885; 
Table of 29-Degree Screw Thread Parts, Acme Standard, 886; The 
British Standard or Whitworth Thread, 887; The Trapezoidal 
Thread, 888. 

CHAPTER IX. BORING 

Boring Machines 220 

Boring Defined, 911; The Horizontal Boring Machine, 912; The 
Vertical Boring Machine, 913; The Lathe as a Boring Machine, 914. 

The Vertical Boring and Turning Mill 223 

Function and Limitations, 921; Description of Parts, 922; Charac- 
teristic Of>erations, 923. 

Boring 225 

Preparation of the Work, 931; Lathe-boring Operations, 932; 
Chucking — Adjustment in Chucks, 933; Adjustment on Face- 
plates, 934; Adjustment on Carriage, 935; Order of Operations for 
Lathe Boring, 936; Order of Operations for Mill Boring, 937. 

Chucks, Boring and Chucking Tools 228 

Chucks, 941; Independent Chucks, 942: Universal Chucks, 943: 
Combination Chucks, 944; Care of Chucks, 945; Boring Bars ana 
Cutters, 946; Chucking Drills, 947; Counterbores, 948; Chucking 
Reamers, 949. 

CHAPTER X. DRILLING 

Drilling Machines 237 

Drilling Machines and Operations, 1011; The Sensitive Friction 
Drill, 1012; The Upright Drill, 1013; Radial and Univereal Drills, 
1014. 

Drilling 244 

Preparation of Work — Laying Out, 1021; Characteristic Opera- 
tions, 1022; Order of Operations, 1023; The Speed of Drills, 1024. 

Drills ^47 

Characteristics of a Drill, 1031; The Flat Drill, 1032; The Lipped 
Drill, 1033; The Scraping Edge Drill, 1034; The Half-round or 
Hog-nose Drill. 1035; The Modified Hog Nose — "D" DriU, 1036: 
The Straight-fluted Drill, 1037; The Twist Drill, 1038; Special 
Drills, Countersinks and Reamers, 1039. 



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xii CONTENTS 

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Drill Shanks, Sockets and Collets 252 

Drill Shanks, 1041; Morse Taper Shanks — Dimensions in Inches, 
1042; DriU Sockets and Collets, 1043. 

Drill Chucks 254 

Light Drill Chucks, 1051; Heavy Drill Chucks, 1052; Tapping 
Chucks, 1053. » » PP *5 

CHAPTER XI. GRINDING 

GiiiNDiNO 258 

Grinding Operations, Hand and Machine, 1111; The Dry Grinder 
and AtUichments, 1112; The Disc Grinder, 1113; The Wet Grinder, 
1114; The Universal Cutter and Reamer Grinder, 1115; The Drill 
Grinder, 1116. 

Universal Grinder 264 

Functions and Limitations, 1121; Description of Parts, 1122; 
Characteristic Operations, 1123. 

Grinding — Hand Abrasive Operations 270 

Hand Grinding, 1131; Hand Surfacing, 1132; Buffing, 1133. 

Grinding — Machine Abrasive Operations 270 

Preparation of the Work, 1141; Discussion and Classification, 1142; 
Principles and Advantages Involved in Cylindrical and Conical 
Grinding, 1143; Discussion of Speeds, Traverse and Temperature, 
1144; Trial Settings, 1145; Chattering, 1146; Remarks and Repu- 
table Practice, 1147; Order of Operations for Cylindrical and 
Conical Grinding, 1148; Lapping, 1149. 

Abrasives and Abrasive Wheels 276 

Carixjnmdum — Scale of Hardness, 1151; Alundum, 1152; Conm- 
dum, 1153; Emery, 1154; Grindstones, 1155; Abrasive Wheels and 
Wheel Speeds, 1156; Numlx»r of Grains, and Character of Surface 
Cut by Tnem, 1 157; Grade or Hardness, 1 158; Favorite Numbers and 
Grades of Abrasive Wheels, 1 159. 

CHAPTER XII. PLANING 

Planing Machines 285 

Classes of Planing Machines, 1211. 
TheShaper 285 

Function and Limitations, 1221; Description, 1222; Characteristic 

Operations, 1223. 
Slotters and Key-way Cutters 289 

Description of Slotting Machines, 1231; Slotter Tools, 1232; Key- 
way Cutters, 1233. 
The Planer 290 

Function and Limitations, 1241; Description, 1242; Characteristic 

Operations, 1243. 

Planing 293 

Preparation of the Work, 1251; Cutting Speeds, 1252; Planing 
Practice — Roughing and Finishing — Side and Down Cuts, 1253; 
Planing Recesses and Grooves, 1254; Planing Bevels or Angles, 1255; 
Under Cuts and T-Slots, 1256; Cuts Terminating in a Shoulder, 
1257; Accuracy and Errors, 1258; Order of Operations for Shaper, 
1259; Order of Operations for Planer, 1259i. 



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CONTENTS xiii 

PAGE 

CHAPTER XIII. MILLING 

Milling ALlchines 298 

Ordinary Tvpes, 1311; Plain Milling Machines, 1312; Vertical 
Milling Machines, 1313; Horizontal Milling Machines and Rotary 
Planers, 1314; Universal Milling Machines, 1315. 

The Universal Miller and Attachments 302 

Functions and Limitations, 1321; Description of Parts, 1322; The 
Universal Dividing Head, 1323: Index Drum, 1324; Tail-stock, 
1325; Raising Block, 1326; Swivel Vise, 1327; Steady Rest and 
Other Attachments, 1328; Characteristic Operations, 1329. 

Milling 309 

Preparation of the Work, 1331; Nomenclature — Terms and 
Operations D?fined, 1332; Influence of Cutter Diameters, 1333: 
Assembling Cuttens, Collets, Collars, etc., 1334; Feeding and 
Speeds, 1335; End Milling Slots, 1336; Cutting Action of Face, 
Side and End Mills, 1337; Swivel Vise Adjustments, 1338; Order 
of Operations, 1339. 

Examples op Milling 314 

Face Milling, 1341; Slot Milling, 1342; Boring and Facing, 1343; 
Keyseating and Fluting, 1344; 0?ar Cutting, Segment and Spot 
Finishing, 1345; Hobbing a Worm Wheel, 1346; Cutting IVvel and 
Miter Gears, 1347; Helical Grooving, 1348; Backing Off Drill 
Lands, 1349. 

Gearing 327 

The Sizing and Cutting of Gear Wheels, 1351; Table of Gear Tooth 
Parts, 1352; Odontographies (Laying Out Gear Teeth) 1353; 
Table for Cydoidal Teeth, 1354; (Grant's Involute System, 1355; 
liaying out the Involute Rack, 1356; Laying Out Internal Involute 
Geara, 1357; Tabl? for Involute Teeth, 1358; Gearing Notes, 
Strength, Speed and Horse-power, 1359. 

Arbors and Milling Cutters in General 337 

Arlx)rs — Dv^scription and Use, 1361; Shell Mill and Screw Arlx)rs, 
1362; Collets, 1363^ Classification and Design of Cuttere and Mills, 
1364; Care of Cutters, 1365. 

Milling Cutters — Specific 340 

Face Milling Cutters, 1371; Side Milling Cutters, 1372; Angular 
Milling Cutters, 1373; End Milling Cutters, 1374; Fonn Milling 
Cutters and Formed Cutters, 1375; Fly Cutters, 1376; Inserted 
Tooth Cutters, 1377.; Slitting Saws and Screw Slotters, 1378; 
Straddle and Gang Mills, 1379. 

CHAPTER XIV. MISCELLANEOUS MACHINE TOOLS AND 
Aa^ESSORIES 

Presses 346 

Classification, 1411; Assembling Presses — Arlwr -^ Hydraulic, 
1412; Die Presses, 1413. 

Dies and Die Making 350 

Dies, 1421; Die Making, 1422. 

Turret Machines 350 

Turret lathes, 1431; Box Tools and Turners, 1432; Screw Ma- 
chines, 1433; Monitor Lathes, 1434; Forming Lathes, 1435. 

Jigs 363 

Drilling and Filing Jigs, 1441; Jig Characteristics and Designs, 



lung 
2;f( 



1442; Templets, 1443. 



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xiv CONTENTS 

PAGE 

CHAPTER XV. SHOP PROCESSES AND KINKS 

Methods of Working Iron and Steel 365 

Annealing — Ordinary, Dry, Water, 151 1 ; Quenching Baths — Brine, 
Zinc-Chloride Solution, Mercury, 1512; Tempering — ^Air, Oil, etc., 
1513; Case-hardening and Other Processes, 1514. 

Coloring Iron and Steel 366 

Preparatoiy Processes, 1521; Bluing, 1522; Blacking, 1523; Chemi- 
cally Obtamed Browns and Blacks, 1524. 

Cleaning Castings and Forcings 367 

Pickling, 1531; Removing Grease and Dirt, 1532; Use of Com- 
pressed Air, 1533. 

Soldering, Sweating, Brazing and Ferro-Fixing . . ... . . 368 

Terms Defined, 1541; Soldering, 1542; Sweating, 1543; Brazing, 
1544; Ferro-Fixing, 1545. 

Miscellaneous Kinks 369 

Forging Square Holes, 1551; Dividing in the Lathe, 1552; Rust 
Joints, 1553. 

CHAPTER XVI. MECHANICS 

Fundamental Principles 370 

Work, 1611; Power, 1612. 

Heat 371 

Theory, 1621; Relation Between Heat and Work, 1622; An Ex- 
periment in Thermodynamics, 1623. 

Power Graphs and Computations 373 

The Indicator Card, 1631; Power and Steam Computations, 1632. 

CHAPTER XVII. POWER-GENERATING MACHINES 

Steam Engines and Turbines 376 

The Steam Engine, 1711; Turbines, 1712; The Dow and Pyle 
Turbines, 1713; The DeLaval Turbine, 1714; The Curtis Turbine, 
1715; The Westinchouse-Parsons Turbine, 1716; Table of Com- 
parative Steam and Coal Consumption, 1717. 

Gas, Oil and Hot Air Engines 386 

Theory and Thermodynamics, 1721; Beau de Rochas* Conclusions; 
Otto and Clerk Cycles, 1722; Discussion of Details and Methods of 
Regulation, 1723; The Diesel Engine, 1724; Fuels, 1725; Operation, 
1726; Naphtha Engines, 1727; Hot-air or Caloric Engines, 1728. 

Hydraulic Motors 396 

Water Wheels, 1731; Turbines, Theory and Discussion, 1732; 
Turbines — Classes and Uses, 1733; Impulse Wheels, 1734; Reac- 
tion Wheels, 1735. 

CHAPTER XVIII. ELEMENTARY ELECTRICITY 

Nomenclature 403 

Standards, Laws and Facts, 1811; Analogies Between the Flow of 

Water and Electricity, 1812; Electric Circuits, 1813. 
Induction and Magnetism 407 

Historical Note, 1821; Magnets and Magnetic I^aws, 1822; The 

Strength of Ele.ctro-magnets and Solenoids, 1823. 
Dynamos and Generators 409 

Description of a Dynamo or Generator, 1831; Principles of the 

Dynamo or Generator, 1832; Commutators, 1833; Armatures, 1834; 

Field Magnets, 1835; Windings, 1836. 



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CONTENTS XV 

PAtiE 

CHAPTER XIX. POWER TRANSMISSION 

Electric Transmission 415 

Efficiency of Electric Systems, 1911; Governing Conditions in the 
Selection of Systems, 1912; Tabulated Transmission Data, 1913; 
Systems of Electrical Distribution in Common Use, 1914; Motors, 
Discussion and Principles, 1915; Motor Speed Regulation, 1916; 
Alternating-current Motors, 1917; Synchronous Motors, 1918; 
Induction Motors, 1919. 

Compressed Air Transmission 423 

Compressed Air, 1921; Air Compressors, 1922; Compressed-air 
Engines and Machines, 1923. 

Hydraulic Transmission 425 

Adaptability and Uses, 1931; Hydraulic Forging, 1932. 

Rope Transmission 426 

Wire Rope Transmission, 1941; Rope Driving, 1942; Systems, 1943; 
Sheaves and Pulleys, 1944; Transmission Rope, 1945; Splicing, 1946. 

Shapt, Pulley and Belt Transmission 436 

Shafting, 1951; Shafting Supports, 1952; Bearings and Hangers, 
1953; Pulleys, Clutches and Couplings, 1954; Arrangement of 
Shafting and Pulleys, 1955; Lining Up Shafting, 1956; Belts and 
Belting, 1957; Belt Lacing, 1958; Horse-power Transmitted by 
Leather Belting, 1959. 

CHAPTER XX. MOTOR DRIVES AND MOTOR-DRIVEN 
MACHINE TOOLS 

Motor Drives 453 

Advantages of Motor Drives, 2011; Relative Costs of Equipment, 
2012; Economy of Motor Drives, 2013. 

Motors for Shop and Machine Tool Driving 458 

Constant-speed Motors, 2021; Variable or Adjustable Speed Motors, 
2022; Compound Motors, 2023; References to other Data, 2024. 

Working Applications op the Various Motors 465 

On the Choice of a Motor, 2031; ConstantHspced Service, 2032; 
Variable or Adjustable Spieed Service, 2033; Drives and Tools 
Requiring Compound Service, 2034. 

Speed Regulation 466 

Speed Ranges, 2041; Speed Control, 2042; Speed Control Relations, 
2043; Systems and Wiring, 2044. 

Horsb-power Requirements 469 

Motor Ratings, 2051; Power Requirements of Reciprocating Tools, 
2052; Campbell's Formula, 2053; Horse-power Reouired to Remove 
Chips of a Given Area, 2054; Horse-powers of tne Motor Equip- 
ments for Various Machine Tools, 2055. 

Index 481 



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CHAPTER I 
INTRODUCTION AND EQUIPMENT 

III. Foreword. Those of us who have had to do with the 
education and training of the technical student know how very 
diflScult it is to meet satisfactorily the insistent inquiry for a 
comprehensive though elementary work on mechanical engineer- 
ing in its relation to machine shop practice. Apprentices, work- 
men and students, each and all, cali for a work free alike from 
pedantic discussions, involved presentations, and that bugaboo 
of so many, complex formulas. To supply such a work was one 
of the author's endeavors. There are still many who object to 
any attempt to convey, by means of descriptions, the content 
of practical processes. However, it is thought that such objec- 
tions are outweighed by the admitted value which recorded 
investigations have as time savers, and furthermore by the free- 
dom obtained from the irksomeness of always having to begin 
at the beginning. In the presentations and discussions the use 
of graphs to illustrate, and in some instances to derive mathe- 
matical formulas, will, it is hoped, be most acceptable to all. 

This first chapter, the bulk of which pertains particularly to, 
and has to do with, students and school shops, finds its justifica- 
tion in meeting the needs which the newly organized industrial 
and trades schools have created for material of this sort. The 
dearth of such material should make its inclusion in a work of 
this kind particularly acceptable to those connected with such 
schools. To the experienced machinist, and those whose use of 
the book will be chiefly for reference, much of the content of this 
first chapter will be found superfluous. To these the author offers 
the advice that they turn speedily to other pages where the sub- 
ject of their inquiry may be found. 

There has been an endeavor, not only to anticipate and answer 
such questions as arise in the mind of the student or appren- 
tice, but also to present briefly such other knowledge of materials 

1 



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2 ' ENGINEERING AND SHOP PRACTICE 

and processes as the ne^s of modern practice seem to demand. 
The work is written primarily for the student and apprentice, 
though it is hoped that, in this day of specialized workmen, it 
may be read with profit by the teacher and journeyman. We 
have had, and continue to have, books on engineering and shop 
practice from the theorist's, layman's and teacher's point of view, 
but the need of such a work from the view-point of the student, 
apprentice and workman has long been apparent. 

The author has made no attempt to exhaust the knowledge 
of engineering in its relation to machine shops, or indeed of any 
one process, nor to take up in detail the process, product and 
each feature of every tool, but purposes to present the material 
of mechanical engineering in its relation to shop practice in such 
a manner as to obtain a maximum amount of definite knowledge 
and mental discipline with a minimum of words. 

112. Character of Instruction. As the work of the machine 
shop generally comes last in a scheme of industrial education, it 
is taken for granted that all the experience with, and knowledge 
of, metals which the student possesses has been gained in the 
foundry and forge shop where heat was the agency by which the 
stubborn metal was rendered tractable and subservient. In 
the machine shop, however, the metals are wrought cold, being 
subjected to processes very similar to those employed in the work- 
ing of wood, though the machines and tools are novel and peculiar 
and the processes altogether new. For the reason then that the 
work of the machine shop does come last, it is the author's pur- 
pose to simply review and emphasize the important points of 
the other shop processes, rather than to take up in detail the work 
of pattern-making, molding and forging. Those who have not 
had the advantage of the work of the other shops, and whose 
concern is mainly that of the machine shop, will find sufficient 
material regarding these processes as they relate to it to enable 
them to understand its important details. 

The difficulty which always obtains in the presentation of any 
process by descriptions alone led to the adoption of certain 
schedules termed *' Characteristic Operations" and *' Order of 
Operations." The efficiency of these schedules has been demon- 
strated by the repeated success which has attended their use in 
the shop. 

113. Shop Ethics. The student, confronted as he is by 



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INTRODUCTION AND EQUIPMENT 3 

these novel conditions and processes, will find the following 
pertinent remarks of more than passing worth: 

Learn to work in harmony with your mates, remembering 
that their rights and privileges are the same as your own. 

Be loyal — that makes for success; be faithful — that's 
honest. 

In the machine shop, as well as anywhere else, it is of great 
importance to give special attention to what is going on at the 
present moment. By so doing, you may prevent the spoiling 
of work, and perhaps serious injury to yourself. 

Keep your individual tools sharp; your locker neat and clean. 

Borrow no private tools. Be considerate in your use of the 
general tools, returning them to the tool-room as soon as possible, 
and in at least as good condition as when they were received. 

A minimum amount of work usually accompanies a maximum 
amount of talk. 

Courtesy demands that you refrain from passing remarks 
concerning the troubles of others — you may soon have some 
of your own. 

When curious or in doubt in reference to your work or machine, 
consult the teacher, assistant or foreman — that's what they 
are hired for. 

Be thoughtful and deliberate. Do your thinking beforehand; 
the afterthoughts of too many people find expression in terms 
more forceful than elegant. 

114. Carefulness in the Shop. The following concise and 
pithy paragraphs relative to the care of self and the care of ma- 
chines are taken from Brown & Sharpens excellent little work 
for apprenticed machinists: 

"If a machine is set wrong it may spoil valuable work. 

''The effect of some mistakes may not always be immediate 
and severe. 

"A pupil may go to a recitation without having studied his 
lesson, and yet be able to answer the questions put by the teacher. 
In a machine shop, however, if a workman makes a mistake in 
running a machine, the machine never excuses him. If he gets 
in the way of a machine, he is always punished, and often with 
extreme severity. A man stopped a planer by half shifting the 
reversing belts, without stopping the countershaft overhead. 
He bent over to look into the place where he had just been 



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4 ENGINEERING AND SHOP PRACTICE 

planing; his leg pushed the operating lever, the planer started, 
and the tool ploughed deep through his skull." 

115. Care of Self. ** Want of care does more damage than wani 
of knowledge'^ [the italics are mine]; hence, care and knowledge 
should be well commingled. It is easier to form a habit than 
to break one off; therefore we should strive to form correct habits. 

"Before beginning to learn machine making we should learn 
that it is dangerous to lean against a machine that is running, 
and that it is important to keep a proper distance from any 
mechanism that is in motion, or is likely to be set in motion. 
It is sometimes convenient to place one's hand upon a moving 
piece, but before doing so one should know the direction of the 
motion, and the place touched should not be the teeth of a gear 
or the teeth of a cutter. If one touches a piece supposed to be 
moving south when in reality it is moving north, one's hand may 
be seriously injured. 

*'In touching a belt that is running, the hand should be kept 
straight, and should touch the belt only upon its edge; if the 
fingers are bent they may be caught between the belt and pulley. 

''Never put your fingers in the way of a machine for fun; in 
short, never play with a machine at all, for it will not stand a 
joke. 

"It is dangerous to set a lathe tool when the work is running, 
and still more dangerous to set a planer tool." 

116. Care of Machine. "Having given our young machine 
maker some points for his own safety, we should Hke to give him 
a few for the safety of the machines themselves. While the 
machine acts according to a blind and unconscious necessity, 
apparently with utter fierceness and cruelty, yet it can be very 
easily injured. Do not allow a tool to run by the work so far as 
to chuck or bore a lathe spindle. Do not score the platen of a 
planer. Do not make holes in the table of a drilling machine. 
Do not gouge the footstock or vise of a milling machine. Do not 
lay a file or any other tool upon the ways of a lathe; they should 
be guarded with the greatest care. Do not cut into a lathe arbor. 

"The running parts of every machine should be oiled at least 
once a day, and perhaps oftener. Slides and other exposed 
bearings should be wiped clean before oiling. If you take a 
machine that some one else has been running, do not trust that 
it has been oiled the same day, oil it yourself. If a machine is 



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INTRODUCTION AND EQUIPMENT 5 

not properly oiled, it makes a damaging report, it roughs up and 
stops, often requiring hours to repair before it will run again. 

** After a machine has thus been stopped, you need not tell 
that it has been properly oiled, because nobody will believe you. 
The evidence of the machine deals only with facts and not with 
fictions. Even though an abundance of oil has been put into 
the oil-holes, the bearings may not have been properly oiled, 
because the oilways are plugged up with dirt. It is a bad sign 
to have the oil remain in the holes without sinking at all, when 
the machine is running. Every oil-hole should be vented so that 
when oil is forced into one place it can be seen oozing from another. 
If an oil-hole is not vented the oil may rest on a cushion of air 
which tends to lift the oil out. If the vept is plugged up it is 
safer to take the bearings apart and clean the oil-ways, but some- 
times a vent can be cleaned by forcing in naphtha or benzine. If 
you have been so unfortunate as to have a bearing roughed, the 
first thing to do is to force in naphtha or benzine; the next thing 
is to take the bearing apart and have the rough places carefully 
dressed. Like many other troubles that have come once, the 
roughing of a bearing is likely to come again. 

*'It can hardly be expected that one can follow the calling of 
a machinist without soiling one's hands, yet there are grades in 
grime, and some grades are more offensive than others. From 
a mechanic's point of view, one machine may be dirty, while 
another is clean. There are work-shops that are kept in a more 
healthful condition than some dwelling houses. 

117. Tools and Work. ''Some workmen arrange their tools 
so that they can be easily reached and do not let files destroy 
one another by throwing them together. The use of a monkey- 
wrench for a hammer indicates poor taste; and to jam a piece of 
finished work in a vise or under a set-screw proves that a man 
lacks in mechanical ability; whatever else he succeeds in, it is 
very unlikely that he can ever become a good workman. Any 
man to whom a bad job is not a lasting mortification shows 
himself deficient in self-respect. A long job may soon be for- 
gotten, a bad one never." 

Instructions as to what is wanted, or how the w^ork is to be 
done, may be had verbally from the teacher or foreman, or 
gathered from the mechanical drawing. The student or apprentice 
should give special attention to these instructions and never 



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6 ENGINEERING AND SHOP PRACTICE 

commence work until he understands thoroughly just what is 
wanted. It is very important that he form the habit of meas- 
uring such stock and castings as are presented to him for machining 
to determine, prior to any work, whether. or not the piece will 
finish to dimension. 

Shop Equipment and Regulation 

121. Machine Tool Equipment for Shop or Laboratory. An 

excellent laboratory equipment for the teaching of machine shop 
practice, suitable for a class of twenty students, would consist of 
the following tools : — 

Ten l^" First-class Engine Lathes, with Chucks and Change 
Gears. 

Two 20'' First-class Engine Lathes, Hendey-Norton Type, 
with Chucks and Taper Attachment. 

One Flat Turret Lathe. 

One 36'' Boring Mill. 

One Small Radial Drill or 26" Medium Upright Drill. 

One 28" x 7" Planer. 

One Speed or Sensitive Friction Drill. 

One IG'' Shaper. 

One Universal Milling Machine. 

One Universal Grinding Machine. 

One Dry Emery Grinder. 

One Wet Emery Grinder. 

One Drill Grinder. 

Two 10'' Speed Lathes. 

One Gas Forge and Air Compressor. 

One Power Hack or Cold Saw. 

One Small Power Press and Dies. 

Eight 4:" or 4^ Heavy Machinist's Vises, attached to Suitable 
Work-benches. 

Ten Sets Vise Tools, with Suitable Lockers or Cupboards. 

Ten Sets Lathe Tools, with Suitable Lockers or Cupboards. 

In addition to the above equipment it is necessary to have 
the tool-room stocked with such general small and measuring 
tools and materials as are mentioned throughout the subsequent 
pages of this book. 

122. The Tool-room. The tool-room and its successful 
management is one of the most important problems which pre- 



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INTRODUCTION AND EQUIPMENT 7 

sents itself to him who has charge of the shop. The tool-room 
is the depository for all the general and special small tools and 
for such small supplies as are easily handled. The tool-keeper 
should be solely responsible for all the tools and supplies under 
his charge, and should exercise as much care in noting the condi- 
tion of the returned tools, as he does in promptly complying with 
the reasonable requests of his mates. 

The two common systems by means of which a workman may 
draw tools from the tool-room are the Check and Record Systems. 

123. The Check System. This system employs the use of 
brass checks, several of which, stamped with the workman's 
number, are issued or presented to him for his personal use. 
When he desires a tool from the tool-room, he makes his request 
and presents a check; this check the tool-keeper places in the 
position of the tool which he gives to the workman. When the 
tool is returned in good condition it is put into its place and 
the check returned to the owner. 

124. The Record System. On pages 8, 9 and 10, are given 
fac-similes of tool and time records; their use is easily gathered 
from a reading, rendering any explanation superfluous. 

125. Tool-room Rules for School Shops. 1. The tool-keeper 
is required to examine and make a daily report of all small 
tools, stating their present condition, and reporting all missing 
or broken articles. 

2. The tool-keeper is not allowed to leave the tool-room 
without permission from the teacher. 

3. The tool-room must always be neat and clean, the tool- 
keeper taking care to see that each tool is in its proper place 
before leaving to wash. 

4. Credit will be given for tool-room work, provided the 
student has successfully performed the same: i.e. has kept the 
tool-room neat, clean and in order at all times. 

5. The student may chip, file and scrape a surface plate 
when not engaged in the legitimate tool-room work. 



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ENGINEERING AND SHOP PRACTICE 

TOOL AND TIME RECORD 

MACHINE SHOP 

Manual Training High School, - Kansas City, Mo. 



Student's Name 

Date Period. 

Time spent at work on Exercise No 

Kind of work done 

Vise or Machine Tool used during period 





Put a Cross opposite 


Tools 


required from Tool Room 




Lathk Set 


Vise Set 


Cross 


Drawer No 


Check 


Cro»» 


Drawer No. . 


Check 












Calipers, 3-in., Outs. Spg. 


Calipers, 6-in., Outs 






" 4-in., Ins 






Center Punch 






Center Gage 






Chalk and Box 






'* Punch 






Dividers 3-in Srcr 






Chalk and Box 






File Cleaner 






File, 12-in. Mill B. Sg. Cut 
" Cleaner 






" Handle 






" 12-in. Flat B. Dbl. Cut 

" 12-in. Mill B. Sing. " 

" 12-in.HalfRd.B.Dbl." 

Hammer, 24 oz 






" Handle 










Lathe Tool, Armst'g No. 1 

" Thread'g Ins. 

" " Leftside 














Scriljer 8-in 






" Bent " 






Slip Stone 






Piece Copper 






Steel Rule 






Slip Stone 






Try Square 






Steel Rule 






" Bbde, 45-60 . . 
Tool Pan • 






Tool Pan 






















Individual Set 
















Cold Chisel 












Cape Chisel 












Diamond P't Lathe Tool . . 












. Round Nose Lathe Tool . . 












Right Side Lathe Tool 












Parting Lathe Tool 












Boring Lathe Tool 












Threading Lathe Tool 























Remarks: Tool Keeper must check all tools returned in good order and 
report all broken ones on this record. 

Tool Keeper, 

This record must be handed to the teacher bpfore you leave the shop. 

Fig. I24a. — a School Tool and Time Record. 



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INTRODUCTION AND EQUIPMENT 



SHOP RULES 



1 . No student is permitted to work in the shop without overaUs, jacket, 
and cap, which must be in good condition. 

2. Students must have on shop clothes and be ready to begin work when 
the tardy bell rings. 

3. Students are cautioned against using tools before the use and opera- 
tions of same have been explained to them. Each tool, bench and machine 
should be carefully examined, and machines turned over by hand, before being 
used, and any defect, damage or loss reported at once. The last user wiU then 
be held responsible. 

4. Each student is held responsible for the equipment of which he has 
charge. All breakage or loss must be made good. 

5. The shop hours must, be devoted to shop work. Loud talking, collect- 
ing in groups and sitting on benches or machines is forbidden. Deportment 
and neatness are important factors in the determination of a student's standing. 

6. With the exception of grinding machines, no machine is tx) bo used 
without f>ermission. 

7. Special permission must be obtained from the teacher before work, 
other than that assigned by him, may be undertaken. 

8. As soon as an exercise is finished it should be stamped with the stu- 
dent's initials and locker number and handed to the teacher. Credit will be 
given [mediately for properly stamped and finished work. Lost exercises must 
be repeated. 

9. Tool and time records are provided on which each student is to record 
the actual time spent on each piece of work, the kind of work, and machine 
tools used during the period. 

10. Students are not to leave the shop without permission. 

1 ] . When through work, the machine, vise, or bench must be cleaned with 
brush and waste. Before leaving the shop to wash, all small tools must be re- 
turned and checked. 

12. A student's report represents not only the quality of the finished 
work, but also the time he has spent upon it and his attitude toward the work; 
i.e. his disposition to attend to business and to profit by given instructions. 
Repeated disorder, inattention, or disregard of shop rules will necesarily result 
in trouble for the student. 

Fig. 1246. — Reverse side of Fig. 124a. 



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10 



ENGINEERING AND SHOP PRACTICE 



EXERCISE AND TIME RECORD 
MECHANIC ARTS DEFT. McKINLEY HIGH SCHOOL 



Name 

Commenced 

No. pes. stock used. 
Total time 



Periods. 

Finished 

. Kind of work done . 

. .on Exercise No 



Dale 


Time 


Equipment Used 


Received from Tod-room 


































1 































Dimensions 


5 1 

1 i 

1 1 
>e 1 


Finish 


Time 


Tools 


Deportment 
Grade on Exerds 



Tool-keeper must check all tools returned in 
good order and report all broken ones at once. 

This record must be handed to the teacher by 
the student before he leaves the shop. 



Tool-keeper . 
Approved' . . 



Fig. 124c. — A School Exercise and Time Record. 
Note: The above record is used in all shops — Joinery, Forgey, etc. 



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CHAPTER II 

MATERIALS 
Iron, Metallurgy 

211. Ores and Their Reduction. This most important of 
metals is also one of the most abundant. The principal ores 
from which iron is obtained are: magnetite, Fefi^, hematite, 
FcjOa, limonite, 2 FeaO, + SRfi and siderite, FeCOg. What is 
commonly known as pig iron is the result obtained from smelting 
iron ore. Ore containing less than 50% of iron is seldom smelted 
in the furnaces of the United States. The ore is put into the 
blast furnace with a fuel and a flux, — a flux being that material 
which, when melted with the ore, promotes fusion by combining 
with the earthy matter and by-products, allowing the metal to 
separate. The fuel is generally coke, coal or .charcoal, and the 
flux limestone. The entire mass is melted under the forced 
draft, and when a sufficient quantity of the ore is reduced to 
metallic iron at the bottom of the furnace, the furnace is tapped, 
and the iron allowed to run into ditches, from which it flows 
into side-pockets; or, as in more recent practice, it is drawn 
directly into molds. In the first instance it is necessary to break 
the pieces apart; this is done just after the iron "sets." This 
product is the commercial pig iron. 

212. Graphical lUtistration of the Metallurgy of Iron. The 
following chart (Fig. 212) was prepared after a thorough investi- 
gation of the various metallurgical processes, and it is believed 
to be a more complete and convenient presentation of the subject 
than any yet published. 

The diagram illustrates graphically the metallurgy of iron, 
tracing its journey from the mine to the market; it affords a 
means of tracing out the various processes and their relations, 
and indicates roughly the kind of iron or steel produced by each 
process. 

From a survey of the chart we see that the refractory ores, 

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12 



ENGINEERING AND SHOP PRACTICE 



and those containing volatile substances, pass first to the Roasting 
or Calcining Furnace; they then go to the Blast Furnace where 
the ore is changed into the commercial pig irons. Again the ore 




may go directly from the mine to the Blast Furnace, or in the 
case of some grades of pure ore it is changed, by the direct process, 
into wrought iron, finding its way to the market as such. The 
product of the Blast Furnace is put on the market as the com- 



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MATERIALS 13 

mercial pig irons; these may, by passing through some one of the 
conversion processes, be made into iron or steel; or they may, by 
way of either of the remelting processes, reach the market as 
cast iron or malleable cast iron. If treated in the Puddling 
Furnace the pig iron is changed to marketable wrought iron. 
Wrought iron when treated by the Cementation Process becomes 
blister steel. This blister steel is passed through the Crucible 
Process and the product reaches the market as tool steel. If 
pig iron is treated by the Open Hearth process it is changed to 
what is known as ingot iron, in which form it goes to the market. 
Treated by the Bessemer Process pig iron is also changed into 
ingot iron. 

If, however, castings are wanted, the pig iron is remelted, 
mixed with scrap, etc., in the Cupola and the product is cast 
iron. When "Charcoal Pig" or any pig iron free from sulphur 
is treated in the Air Furnace and cast, hard or white castings 
result; these brittle castings now pass to the Annealing and 
Decarburizing Furnace where they are changed into malleable 
cast iron. Cupola castings are sometimes treated in the Annealing 
and Decarburizing Furnace, in which case they become malleable 
cast iron. 

213. Metallurgical Notes. Cast iron usually contains over 
3% of carbon; cast steel anywhere from .06% to 1.6%, according 
to the purpose for which it is used; wrought iron from .02% to 
.10%. The quality of hardening and tempering which formerly 
distinguished steel from wrought iron is now no longer the dividing 
line between them, since soft steels are now produced, which by 
the ordinary blacksmith's tests will not harden. All products of 
the crucible, Bessemer and open-hearth processes are now com- 
mercially known as steel. 

Pure iron is extremely infusible, its melting point being above 
3000° F. It is malleable, tough and ductile and as far as can 
be determined from the strength of steel, it has an extreme 
tensile strength between 38,000 and 39,000 pounds per square 
inch. By different processes cast iron and wrought iron are 
produced directly from pig iron; the cast iron being produced 
by melting the pig in a cupola and casting in molds. In struc- 
ture it is hard, crystalline and brittle. 

The other properties which we note in cast iron and steel 
are due principally to the presence of carbon, the most of which 



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14 ENGINEERING AND SHOP PRACTICE 

is absorbed from the fuel in the process of reduction. With the 
addition of carbon the fusibility of iron increases, cast iron fusing 
at from 2000° F. to 2500'* F.; the average temperature at which 
steel fuses being about 2550° F. 

The addition of carbon renders iron and steel hard and brit- 
tle. In cast iron only a portion of the carbon is chemically 
combined with the iron, some of it existing as free or graphitic 
carbon. This constitutes the chief structural difference between 
cast iron and steel. Cast iron is then a chemical combination 
of iron and carbon, generally containing some other elements, 
as silicon, phosphorus, sulphur and manganese, which give to 
it certain peculiar characteristics, according as they vary in 
quantity. 

214. Influence of Carbon, Manganese and Phosphorus. Car- 
bon is the element above all others which steel makers employ, 
where price is a consideration, in the production of steels of 
required physical properties. In general, it may be stated that 
a given content of carbon will confer a greater hardness and 
strength with less accompanying brittleness than any other 
element. Certain exceptions, however, must be made in the 
cases of the hard steels containing chromium, manganese and 
tungsten. It is well known that every increment of carbon 
decreases slightly and regularly the ductility of iron, and increases 
its hardness, brittleness under shock, and its liability to crack 
and check under conditions of sudden heating and cooling. The 
combined carbon content is always small, seldom exceeding one 
and one half per cent.; yet the effect of even small increments is 
strikingly illustrated by the fact that an increase of yj^ of one 
per cent, will give an increase in tensile strength of about 1000 
pounds per square inch. 

If a piece of red-hot steel (iron plus combined carbon) be 
suddenly quenched in cold water, a compound of extreme hard- 
ness results; the carbon and iron in the metal combining in some 
peculiar way which is not thoroughly understood. A carbon 
content of 1% gives about the limit of useful hardness, the higher 
carbons producing steels which increase so rapidly in brittleness 
that their usefulness is all but destroyed. 

The following conclusions are taken in the main from the 
recorded investigations of H. H. Campbell, and are given in his 
book, *'The Manufacture and Properties of Iron and Steel," as 



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MATERIALS 15 

the result of extended experience covering several hundred heats 
of both acid and basic open-hearth steel. 

Manganese. Probably the most important function which 
manganese serves is that of giving ductility while the steel is 
hot so that the piece may be rolled and finished without tearing. 
Above .60%, while adding to the tensile strength, it does not 
materially decrease the ductility; however, though not proven, 
it seems slightly to increase its liability to break under shock. 
An increase of yj^ of one per cent. (.01%) of manganese has very 
little effect upon acid steel unless the content exceeds .60%, 
but it raises the tensile strength of basic steel about 85 pounds 
per square inch. 

Phosphorus. This element has little effect upon the hot 
properties of steel, but produces what is commonly termed *'cold 
shortness," a term used to designate great brittleness in the 
finished steel. Phosphorus always exists as an impurity, and of 
all the elements commonly foimd in steel, it stands pre-eminent 
as the most undesirable. Its tendency to produce coarse crys- 
tallization, and the consequent reduction in the temperature at 
which it is safe to heat steel, make it highly objectionable in the 
rolling-mill. 

The phosphorus content of ordinary steels is always limited 
to .1% while in special steels much lower limits are specified. 
An increase of yJiy of one per cent. (.01) % of phosphorus raises 
the tensile strength of acid steel about 890 pounds per square 
inch and of basic steel about 1050 pounds per square inch. 

Carbon — Manganese — Phosphorus. The following formu- 
lae will give the ultimate tensile strength of ordinary open-hearth 
steels in pounds per square inch, the carbon, manganese and 
phosphorus being expressed in units of .001% and a value being 
assigned to R in accordance with the conditions of rolling and 
the thickness of the piece. 

The formula for acid steel is: 

38600 -h 121 Carbon -h 89 Phosphorus + R = Ultimate Strength. 
The formula for basic steel is: 

37430 -h 95 Carbon 4- 8.5 Manganese + 105 Phosphorus 4- R = 
Ultimate Strength. 

The metals from which these data were derived were ordinary 



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16 ENGINEERING AND SHOP PRACTICE 

structural steels ranging from .02% to .35% carbon, and it is 
unlikely that the formulas are applicable to higher steels or to 
special alloys. In the case of acid steels an increase in manga- 
nese above .60% will raise the tensile strength above the amount 
given by the formula, the increment being quite marked when a 
content of .80% is exceeded. 

In steel containing from .30% to .50% of carbon, the value of 
the metalloids is fully as great as with lower steels, while the 
presence of silicon in such metal in proportions greater than .15% 
seems to enhance the strengthening effect of carbon. In steels 
containing less than .25% of carbon, the effect of small propor- 
tions of silicon upon the ultimate strength is inappreciable. 

215. Influence of Chromium and Nickel. Chromium is em- 
ployed to give an extreme hardness to steel, the peculiar char- 
acteristic being that no quenching or tempering is required. The 
addition of chromium up to 5%) increases the tensile strength of 
steel and its resistance to shocks, but aBove this percentage the 
tensile strength is lowered. 

Nickel imparts to steel a high elastic limit and great tough- 
ness under shock, and in combination with carbon prevents what 
is known as '* sudden rupture," though its influence is not always 
uniform. Nickel is used to obtain a steel that will withstand the 
heavy shock and torsional tests that are required of armor plate 
and special forgings. 

216. Influence of Silicon and Sulphur. Silicon cannot be 
classed among the highly injurious elements like phosphorus and 
sulphur, for it seems to exert but little influence on the mechanical 
properties of steel even when the content is as great as 5%. All 
attempts at welding silicon steel are unsatisfactory except in 
steel castings where up to .4% of silicon in the mixture is per- 
missible; anything but a trace of silicon is seldom found. Silicon 
has a tendency to make cast steel creamy and sluggish, though it 
will run better in the small passages of a mold than ordinary 
steels; which latter are rendered slow by the sputtering and 
consequent impediment to the passages which occurs when the 
ordinary steel is cast. 

Sulphur is an injurious content and exists as an impurity, 
having just the opposite effect from that of manganese. It not 
only injures the rolling qualities of steel, producing what is 
known as "red-shortness," causing it to crack and tear, but it 



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MATERIALS 17 

lessens its capacity to weld. In its effect upon the cold proper- 
ties of steel, sulphur seems to exert no appreciable influence within 
the limits of the common content, which varies from .02% to 
.10%. 

217. Influence of Tungsten, MolyMenum and Vanadium. 
Tungsten. The effect of tungsten, in conjunction with over 1.5% 
of manganese in tool steel, gives extreme hardness and brittleness 
and the peculiar characteristic, like that of chromium, of requiring 
no quenching or tempering, producing a steel almost as hard 
when cooled slowly in air, from a forging heat, as carbon steel 
when cooled in water. It is the chief element in the production 
of the self-hardening tool steels; its valuable properties having 
been discovered by Robert Mushet about 1865. Tungsten is not 
the true hardener but plays the important part of the mordant 
by means of which the alloy produced is enabled to contain a 
larger combined carbon content. 

Molybdenum was substituted in the Taylor-White process 
for the tungsten in the production of modem high-speed tools, for 
the reason that one part of molybdenum effects approximately 
the result of two parts of tungsten; that is, it combines with the 
chromium in the same manner as tungsten and produces the new 
quality of "red hardness," which is the main feature of the 
Taylor- White discovery. However, it was discovered, that, while 
molybdenum produced the self-hardening properties and brittle- 
ness of tungsten it was not as satisfactory an element, because 
the effect was irregular; that is, tools of the same chemical com- 
position, apparently treated alike, gave large variations in cutting 
speed and possessed a peculiar brittleness and tendency to fire 
crack. For these reasons molybdenum was discarded. 

Vanadium like carbon, is capable of producing great changes 
in the physical properties of steel by the addition of very small 
percentages. It has a tendency to cause brittleness, but vana- 
dium steels excel all others in their ability to resist dynamic 
stresses. Mr. Taylor states that their experiments indicate the 
probability that the good effects of vanadium in high-speed 
steels are derived from its chemical property as a cleanser of the 
steel during the operation of melting, rather than as a very 
valuable property of the steel after it is melted. In its action 
as a cleanser it probably unites with some of the obscure oxides 
and carries them off in the slag. 



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18 ENGINEERING AND SHOP PRACTICE 

Vanadium should not be substituted for chromium in tool 
steelS; but should be added to the mixture in melting in quantities 
of from .15% to .35%; these are as effective as greater quan- 
tities in the mixture. The best high-speed steel produced contains 
.29% of vanadium. 

2i8. Influence of Aluminum, Cobalt, Tin and Titanium. 
Aluminum. Mr. Campbell makes the following remarks concern- 
ing aluminum: ''It is hardly necessary to discuss at length the 
effect of aluminum upon steel, for although it is often used to 
quiet the metal, it unites with the oxygen of the bath and passes 
into the slag." Sometimes a very small percentag>3 remains in 
the steel castings. 

The addition of .5% of aluminum increases the tensile strength 
between 3000 and 8000 pounds, raises the elastic limit in about 
the same proportion and injures very materially the elongation 
and contraction of area. The addition of another .5% does not 
have much effect on the ultimate strength or elastic limit, but 
still further decreases the ductility of the metal and at from 2% 
to 3% it causes great brittleness. The effect upon the strength 
and ductility is more marked in low than in high steels. The 
addition of .5% to 1% to cast iron increases fluidity and makes 
casting possible with the whiter irons. When melting, the addi- 
tion of a proper amoimt of aluminum will ''kill" the most "fiery" 
of steels and allow it when "dead" to pour like the dead melted 
silicon steels. 

Cobalt, Tin and Titanium. In a paper before the French 
Society of Civil Engineers, M. Guillet, 1907, brings out the fol- 
lowing points: Cobalt, Tin and Titanium in steels enter into 
solution in the iron and the carbon exists therein — at least 
within the range of the experiments made — in the shape of iron 
carbide. The mechanical properties of these steels do not seem 
to promise any industrial application thereof. They do show 
very clearly, however, the marked difference between tin, tita- 
nium and silicon steels on the one hand and nickel and cobalt on 
the other. 

219. Table of Physical Properties. The graph (Fig. 219a) 
though of more than passing interest here, is self-explanatory. 
In the table of physical properties, on page 20 (Fig. 2195) compiled 
from recent authorities, average values are given. The atomic 
weight of iron is 56. 



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MATERIALS 



19 



1.75 



UBD 



t86 



.75 



M 















































































Graph showiu^r the effect of the 




















lyurDon coDseni/ m tne proaucuon' 
of Iron ond steel 








1 
































1 


t,t 1 






























1 


i 






























1 


1 






























ii 




1 
1. 




fttrnt 


Iteel-' 






! 
















p 




j 












1 
















11 


U 














1 
1 
1 

1 
















1 


^ 








■tmI r 


trr\\. 




1 
1 
1 k 
















1 


f 


1 I 






||«J o 






1 
1 
















1 


1 














1 

1 
















1 


i 


n 




rorKM 
tmttt. 


VJ 


^- 




1 






roug 










1 


i 


i 




'Z 


DlM.1 

miita 


Cuuw 


*/ 
















1 


1 




1 

^ 


\ 


LMkal 


loUMi 


kChIa 


•jl 
















1 


i 




1 




% 


lll..li 




















^ 


•li'*^ 


1 






1 






NX& 


% 


TiBoju'W** 














1 

^ 


a. 


Pt 


^^ 


g^ 


^m 


^^^ 


^ 


|J« 


^ 


^ 


^?^ 


Ssrr 







w 



ao' 



16' 20* 25* 

Probable Elongation in Inctiet 

Fio. 2I9a. — PLysical Effect of the Carbon Content. 



^' 



40' 



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20 



ENGINEERING AND SHOP PRACTICE 



Cast Iron 



Wrought 
Iron — 



Steel 



2»w 



7.218 

7.70 
7.854 



1298 

1138 
1170 



h 

1^ 



2300 

2912 
2550 



.2604 

.2779 
.2834 



.00000617 



.00000686 



.00000599 

to 
.00000702 



8 

Is 



35.9 

43.6 
39.7 



ll 



12 

to 

14.8 

Swe- 
dish 
16 



•c 

I 

3 

•3 



17,000,000 
26,000,000 

30,000,000 



Ultiuate 

Strength in 

Lbs. pkr Sq. 

Inch. 



I 



20,500 
50,000 

70,000 



95,000 
50,000 

70,000 



Fig. 2196 — Physical Properties of Iron and Steel. 

Pig Iron 

221. Classification of Commercial Pig Irons. The classifica- 
tion of pig iron by fracture, on account of its unreliability, is 
about obsolete, and makers of pig iron rely solely on the chemical 
analysis. The modem classification, therefore, states the maxi- 
murti or minimum quantities of the elements which a given grade 
of pig shall contain. Accordingly we have: 

222. Bessemer. Bessemer iron must not exceed 2.5% of sili- 
con, 1% of phosphorus, .05% of sulphur, while the manganese 
may vary from .3% to 1%. Bessemer iron is used chiefly in the 
manufacture of steel ingots and for such products as are obtained 
from them. 

223. Foundry. Foundry iron, though similar to Bessemer 
iron, may contain from 2% to 4% of silicon, and phosphorus up 
to 1%, while the .05% of sulphur and the .3% to 1% of manganese 
remain the same. Foundry iron, on account of its flowing well, 
may be used for intricate castings. 

224. Charcoal. Charcoal iron is so called because it is made 
with charcoal, to eliminate the sulphur found in other fuels, and 
for this reason it is very low in sulphur. It should contain less 
than 2% of silicon, not over 1% of phosphorus, less than .01% 
of sulphur and not more than 1% of manganese. 



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MATERIALS 



21 



225. Basic. Basic iron should not contain over 1% of silicon, 
although the phosphorus content may vary from .3% up to as 
high as 1%; it should rarely exceed .4%. Basic iron should 
never possess more than .05% of sulphur and 1% of manganese. 

226. Ferro-Silicon. Ferro-silicon iron is used chiefly as a 
softener in a mixture of hard grades of pig iron. It generally 
contains from 6% to 16% of silicon; from .5% to 1.5% of phos- 
phorus, sulphur from .01% to .05% and manganese up to 3%. 

227. Gray Forge. Gray forge iron is the poorest and cheapest 
iron on the market. It is used chiefly for the manufacture of 
water pipes and the production of wrought iron. It generally 
contains less than 1% of silicon; is high both in phosphorus and 
manganese, and often as high as .1% in sulphur. 

Cast Iron 

231. Classification and Analyses of Standard Cast Irons. The 

following classification and analyses of cast .iron is compiled from 
data submitted by the committee appointed by the American 
Foundrymen's Association to investigate and standardize the 
product: 



Class of Iron 



Chill Roll 

Gun Metal 

Car Wheel 

General Machinery 

Stove Plate 

Besaemer 



95.75 
95.12 
94.99 
94.10 
92.47 
93.75 



i 



2.45 
2.47 
2.36 
3.31 
4.00 
3.77 



I 



.061 
.76 
1.07 
.58 
.19 
.49 



I 



3.06 
3.23 
3.43 
3.89 
4.99 
4.22 



.84 

.73 

.78 

1.30 

2.47 

1.52 



I 



.547 
.463 
.364 
.433 
.508 
.083 



I 



.071 
.059 
.132 
.053 
.094 
.059 



.285 
.408 
.306 
.224 
.265 
.326 



1^ 

?3 



4487 
4264 
3610 
3111 
2530 
2430 



I 

?.9 



.090 
.110 
.070 
.072 
.078 
.100 



232. Malleable Cast Iron. The description submitted by the 
"nomenclature committee" at the Brussels Congress of the Inter- 
national Association for Testing Materials, 1906, is as follows: 
"Iron which when first made is cast in the condition of cast 
iron, and is made malleable by subsequent treatment without 



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22 



ENGINEERING AND SHOP PRACTICE 



fusion ... is not truly a variety of cast iron but rather forms 
an independent species of iron because it lacks the essential 
property of cast iron, viz., its extreme brittleness." Malleable 
cast iron was generally made by subjecting ordinary castings, 
preferably of charcoal cast iron, to a process of decarburizing and 
annealing in an annealing furnace. It is the practice now to 
select a suitable pig iron and remelt it in an air furnace instead 
of in the cupola — the air furnace possessing several advantages 
over the cupola for this purpose. The resultant "hard" or 
'* white" castings contain little or no graphitic carbon and are 
treated in the usual manner as follows: The castings are packed 
in hematite ore or peroxide of manganese contained in closed 
cast-iron boxes. The furnace is raised rapidly to the maximum 
temperature, and at the close of the operation allowed to cool 
very slowly. With ordinary castings, the operation requires 
from two to five days, while the larger pieces may take as long as 
two weeks. Malleable cast iron, though very brittle when hot, 
may be hammered into any desired shape when cold. The 
following data was compiled by Professor Johnson: 





Totol 
Carbon 


Combined 
Carbon 


Graphitic 
Carbon 


Manga- 
nese 


Silicon 


PhoB- 
phonis 


Sulphur 


Before Annealing 
After Annealing. 


3.04 
2.66 


2.85 
0.31 


0.19 

2.35 


0.21 
0.21 


0.73 
0.72 


0.154 
0.153 


0.050 
0.050 



Loss of carbon, 0.38; maximum tensile strength per square 
inch, 49,810; elongation 6.23%. All bars were cylindrical in 
section and |J inch in diameter. They were not machined, as 
skin is about twice as strong as the interior per unit of area. 
These figures represent an average of 42 test bars, annealed 108 
hours. 

233. Annealed Castings. Castings may be annealed by pack- 
ing them in a cast-iron box with a mixture of one half bright 
cast-iron turnings or filings and one half pulverized charcoal. 
To keep the castings from warping, and to heat them more uni- 
formly, there should be a layer of the mixture between them. 
The " pots'' are then placed in the oven and brought to a bright 
cherry red, when they are allowed to cool off. If very soft 
castings are desired, the furnace should be held at a bright cherry 



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MATERIALS 23 

red for two or three hours. It is absolutely necessary that the 
castings be left in the box to cool off. 

234. Case-hardened Castings. The surface of cast iron may 
be hardened in the following manner: The piece is heated to a 
cherry red, and the surface rubbed or coated with potassium 
cyanide or potassium ferro-cyanide; it is then suddenly chilled 
by dipping in water. The cyanide, by carbonizing the iron to 
about a depth of ^ inch, converts it into steel, which we know 
may be hardened by heating and suddenly cooling. 

Castings may also be case-hardened by a process similar to 
that of producing malleable iron, with the exception that, instead 
of imbedding in the ore, the pieces are imbedded in granulated 
raw bone. After packing, the boxes are luted with clay and 
covered. The furnace is then brought to a bright cherry red, 
and held at that heat from three to ten hours, according to the 
depth of the case-hardening desired and the size of the pieces to 
be case-hardened, after which the pieces are removed from the 
boxes and suddenly cooled. 

The Colliery Engineer Co. print the following formula for 
a case-hardening solution for cast-iron dies: *'Dies, etc., made of 
cast iron may be case-hardened by heating to a cherry red, and 
then chilling them in the following solution: 1 quart of oil of 
vitriol, 4 pecks of salt, 8 pounds of alum, 1 pound of yellow prus- 
siate of potash, 1 pound of cyanide of potash, 2 pounds of salt- 
peter, which ingredients have been dissolved and mixed in 40 
gallons of water, the cyanide of potash and yellow prussiate of 
potash being dissolved in hot water and the others in cold. If 
one heating and chilling does not harden the die enough, the 
process may be repeated. 

235. Uses, Adaptability and Comparison with Wrought Iron 
and SteeL Comparing cast iron with wrought iron and steel, we 
have: cast iron is more easily given, by casting, any desired shape. 
It oxidizes less easily, that is, rusts less than wrought iron or 
steel; it has a very high compressive (crushing) strength. On 
the other hand, it is liable to hidden defects, rendering its strength 
uncertain. It cannot be forged, and does not withstand shocks 
and jars. It stretches but little, and owing to its brittleness 
breaks off with but little warning. It is also subject to internal 
stresses, set up from unequal cooling in the mold; its tensile 
strength is comparatively low. It is used by engineers in con- 



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24 ENGINEERING AND SHOP PRACTICE 

struction, where great compressive strength is desired, and in 
machine details where shape, mass and weight are of more im- 
portance than strength. 

Wrought Iron 

241. Manufacture — Norway, Charcoal, Puddled and Fagot 
Irons. Wrought iron is the product obtained by extracting the 
carbon from cast iron, by passing the blast through it or over 
it, while it is in a molten condition. During the operation, the 
oxygen of the air unites with the carbon in the iron, and passes 
off as carbonic acid gas. This process leaves the iron porous and 
pasty; it is now hammered or rolled into ingots or blooms, and 
forged into bars or shapes. Sometimes it is cast and the bloom 
reheated and rolled; in either event it is necessary — to obtain 
good iron — that it be reheated and rolled several times in order 
to render the product flawless and homogeneous. The excellence 
of Norway and other Swedish irons is due largely to the fact that 
charcoal, being free from sulphur, is used during the process of 
melting; although part of the good qualities are due, in a measure, 
to the purity of the ore. 

The best grades of charcoal iron should successfully withstand 
the test of being bent double, hammered down and straightened 
while cold, without showing signs of fracture. 

In the puddle process of producing wrought iron, the cast 
iron is melted in an open hearth with iron ore, which contains 
the necessary amount of oxygen; the flame passing over the 
mass and removing the impurities. It will be seen that wrought 
iron is the result of a series of welding operations which give to 
it its fibrous nature. 

What is known as fagot iron is the product obtained by 
welding together wrought-iron scraps, which are subsequently 
forged into the desired shape. 

The chemical composition of a good pure wrought iron whose 
tensile strength was 51,000 pounds was: silicon .073, phosphorus 
.078, sulphur .005, manganese .005, carbon .042, and slag .974, 
the values being given in fractions of 1%. However, it is found 
that the marked difference in the qualities of irons are caused 
more by different methods of treatment than by difference in 
composition. 



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MATERIALS 25 

242. Properties. Comparing wrought iron with cast iron, we 
have: wrought iron is the tougher and is capable of withstanding 
a greater tensile and transverse stress than cast iron. It is more 
capable of withstanding shocks and also stresses due to changes 
in temperature; possesses greater ductility and gives more warning 
of fractures. On the other hand, wrought iron cannot be melted 
and cast, nor is it easy to give to it a desired shape. However, 
two pieces of wrought iron, when subjected to a proper tempera- 
ture, may be welded — united by a process of hammering when 
at the proper temperature. 

243. Commercial Designation. The commercial terms indica- 
tive of the wide variation in the quality of wrought iron are: 
common bar, best, double best, triple best, and cold rolled. 
The process of cold rolling not only greatly increases the elastic 
limit and the strength, but produces on thie iron a polished 
surface. This latter process, however, reduces its ductility. 

244. Working. Wrought iron is the most easily worked 
material with which the smith has to deal. Owing to the lack 
of carbon in its composition, it does not harden by being suddenly 
cooled from a high temperature; however, it may be case-hardened 
in a manner similar to that described for case-hardening cast iron. 

Steel, Commercial Steels and their Production 

251. Classification. Since the extraction of carbon from cast 
iron renders the wrought iron tough, ductile and soft, it follows 
that it is possible to obtain such a mixture of wrought iron and 
carbon as will possess some of the excellent qualities of both 
wrought iron and cast iron. This product, known as steel, may 
be divided according to its process of manufacture into four 
general divisions which, according to Metcalf, are: 

Converted or Cemented Steel. 

Crucible-Cast Steel. 

Bessemer | ^^^. | Cast Steel. 

Open-Hearth | ^f^ | Cast Steel. 

252. Converted or Cemented. Converted or cemented steel 
is divided, according to its manufacture, into blister, German, 



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26 ENGINEERING AND SHOP PRACTICE 

shear or single-shear and double-shear steel; however, though the 
process of production of these brands be interesting, they have 
been superseded by the cast steels. 

253. Blister. Blister steel is manufactured by surrounding 
small (J inch square ) bars of charcoal iron by some form of car- 
bon, such as charcoal or bone ash, in a suitable vessel, which is her- 
metically sealed, and then subjected to an even high temperature 
for some days. Under this action the carbon penetrates the iron, 
and when the bars are removed they are found to be covered 
with scales or blisters, having been converted from tough wrought 
iron to highly crystalline steel. Oftentimes a better grade of 
steel is produced by removing the scales and blisters and again 
subjecting the bars to a cherry heat for a few days, thus producing 
a more uniform distribution of the carbon. 

254. German. German steel is produced by heating blister 
steel and rolling it directly into finished bars. 

255. Single and Double Shear. Single-shear steel is produced 
by subjecting blister steel to a high temperature, welding it 
under the hammer, and then rolling it into bars. 

Double-shear steel is produced by welding together broken 
bars of single-shear steel, which are then hammered or rolled into 
desired shapes, thus producing a more uniform product. 

256. Crucible Cast. Crucible-cast steel may be obtained in 
two ways, the aim being to produce a steel uniform and homo- 
geneous in stnicture. In the first, bars of blister steel are broken 
up and melted in a crucible, the contents of which are then cast 
into ingots and rolled into bars. This produces the finer qualities 
of the crucible and cast steels now on the market. By far the 
larger portion of cast steel is produced by packing Swedish iron, 

'together with charcoal, in a sealed vessel the contents of which 
are then melted and poured — with the contents of several other 
similar vessels — into a large ladle. The metal in this large 
ladle is then cast into ingots which are subsequently forged under 
the hammer or with rolls. 

257. Bessemer. Bessemer steel. The soft or mild machinery 
steels of commerce contain but little carbon, show but a few of 
the characteristics of steel, and are but little better than iron. 
They are produced by both the Bessemer and the open-hearth 
processes. The Bessemer process consists of decarbonizing molten 
cast iron by blowing through it a blast of air; the requisite amount 



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MATERIALS 



27 



of carbon is then obtained by adding to it sufficient quantities of 
Spiegeleisen — an iron of known chemical composition, rich in 
carbon and manganese. After this product is thoroughly mixed, 
it is cast into ingots which are subsequently rolled or forged into 
desired bars and shapes. 

258. Open Hearth and Puddled. The open-hearth or puddled 
steels are made by what is known as the Siemens-Martin process, 
which consists of adding to cast iron which has to some extent 
been decarbonized, in an open-hearth furnace, a certain amount 
of scrap wrought iron. The molten mass is continually stirred 
imtil it becomes somewhat spongy and granular, after which the 
mass is taken out and cast into ingots, which are subsequently 
forged or rolled into the desired shape. By a judicious propor- 
tioning of the wrought and cast iron, steel of almost any desired 
grade of carbon may be produced. 

259. CarlH>n Steels. This term generally applies to steels 
used for cutting and small tools and is what might be termed a 
pure steel as it is a combination of iron and carbon, other ele- 
ments appearing only as impurities or as they have been inserted 
in small quantities by the steel-maker to assist in some detail in 
the process of manufacture. The carbon content ranges from 
50 to 150 points, that is, .5% to 1.5%. An increase of .01% 
increases the tensile strength about 1000 pounds per square inch, 
and while 50-point carbon is hard enough for some cutting tools, 
100-point carbon gives, when tempered, the limit of hardness 
of this kind of steel, being all but hard enough to resist being 
scratched by a heavily loaded diamond. 

Structural steel contains from .02% to .35% carbon. 

The following table from data by F. W. Taylor gives the 
chemical analysis of some of the best grades of ordinary carbon- 
tool steels, hardened in water, together with their relative cutting 
speeds. 



Kind of Steel 


Carbon 




Silicon 


Phosphorus 


SuliAur 


Speed in Me- 
dium Steel 


Jessup 

Midvale O.H. . 
Midvale O.H. . 

Sanderson 

Stirling Spec. . 


1.047 
0.992 
0.681 
1.072 
1.240 


0.189 
0.318 
0.198 
0.291 
0.156 


0.206 
0.256 
0.219 
0.148 
0.232 


0.017 
0.037 
0.024 
0.014 
0.016 


0.017 
0.020 
0.011 
0.011 
0.006 


16 Ft. 
16'-8' 


15'-8' 
16 Ft. 



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28 ENGINEERING AND SHOP PRACTICE 

Steel, Alloy and High Speed 

261. Chrome Steel. Carbon steel, by the addition of 1% or 
2% of chromium, produces a metal, not only extremely hard but 
one which is self-hardening. It is fine-grained and very hard in 
the hardened state but does not stand redressing, becoming 
inferior because of the rapid oxidation of chromium as it is 
redressed. J. W. Langley says that chrome, like manganese, is a 
true hardener of iron, even in the absence of carbon. 

A tool of high chromium, 3% to 4%, with the proper amount 
of tungsten, invariably produces a high-speed tool steel even 
when the manganese content is low. The best high-speed tool 
steels now contain from 5% to 6% of chromium. It is suitable to 
use in the manufacture of some metal-cutting tools or armor plate 
and shells. 

262. Nickel Steel. Nickel steel may be purchased in the open 
market with a nickel content from up to 35% and a carbon 
component between .1% and 1.%. It possesses a remarkable 
tensile strength and ductility, a high elastic limit and homo- 
geneity and a great resistance to cracking. Tests show a tensile 
strength of from 100,000 to 275,000 pounds per square inch, with 
an elastic limit of from 40,000 to 74,000 pounds per square inch 
and an elongation of from 3% to 55%. 

Kent says that sudden failure or rupture of this steel would 
be impossible, for it seems to possess the toughness of rawhide 
with the strength of steel. An alloy of 27% nickel is practically 
non-corrodible and non-magnetic. The effect which nickel pro- 
duces on steel is to raise the elastic limit and to give great tough- 
ness under shock, the nickel evidently preventing the shortness 
caused by the carbon to the extent of even assisting the latter to 
exercise its strength-giving properties. The effect of nickel is 
not always uniform; thus percentages up to 8% increase the 
tensile strength and elastic limit, while in the zone between 8% 
and lb% brittleness is produced; but at 16% the strength and 
elastic limit are returned; again, steel with 2% of nickel and .9% 
of carbon cannot be machined. With less than 5%, of nickel it 
can be worked cold provided the carbon content be low; as the 
proportion of nickel raises cold working becomes difficult, though 
it forges easily whether the nickel content be great or small. 

The manganese content in nickel steel is most important; it 



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MATERIALS 



29 



would seem that without its assistance in proper proportion, the 
conditions of treatment would not be successful. The carbon 
content is also important for upon it depends the strength and 
hardness. In the heat treatment of this alloy, which is always 
beneficial, nickel overcomes the tendency to burn, and the extent 
to which it may be swayed by heat treatment is illustrated in 
the following table by E. F. Lake: 



Hardness 


Tensile Strength 
Lh». Per Sq.Tn. 


Elastic Limit 
T.h«. Per Sq. In. 


Elongation in 
2" Per Cent. 


Reduction of Area 
Per Unit 


Annealed 

Medium Hard . . 
Hard 


88,000 
130,000 
220,000 
225,000 


60,000 

130,000 
190,000 
225,000 


28 

20 

12 

8 


58 

6 

37 


Very Hard 


19 



The composition of the above steel was Nickel, 3%; Carbon, 
0.30%; Manganese, 0.40%; Phosphorus, 0.05%, and Sulphur, 
0.04%. ♦ 

As is well known, nickel steel is eminently adapted for ordi- 
nance work; and armor plate, surface-hardened by the Harvey 
process, is used in all the navies of the world. On account of its 
ability to withstand heavy shock and torsional tests, nickel steel 
is adapted for crank and propeller shafts, connecting rods, explo- 
sive engine and automobile work. 

263. Nickel-chrome Steel. An alloy of nickel, chrome and 
carbon, developed during the last decade, bids fair to occupy as 
high a place as any commercial steel manufactured. It is used 
chiefly for high-grade machinery that requires a steel of great 
resistance to shock and torsional stresses, high elastic limit and 
great tensile strength. Chromium, in conjimction with nickel, 
overcomes a tendency of lamination and produces an elastic limit 
beyond all expectations. When nickel chrome steel is given a 
proper heat treatment, it is practically a homogeneous mass 
showing no grain or fiber and so manifesting an extraordinary 
power to resist shocks. 

The action of chromium in the alloy becomes conspicuous 
above a content of 1%; and with 2% great difficulty is expe- 
rienced in cutting cold without the use of a special tool steel. 

Nickel-chrome steel is used largely for auto work, propeller 
shafts, and where the price is sacrificed to obtain quality. The 



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30 



ENGINEERING AND SHOP PRACTICE 



following table, the last two lines of which give the specifications 
adopted by the Association of Licensed Automobile Manufac- 
turers, gives the composition of nickel-chrome steels together 
with their remarkable physical properties: 



Kind of Steel 



After Heat Tkkatxent 



^^3^ 



3 B « . 



Is 



Nickel-Chrome. . 
Chrome-Nickel . , 
25C Auto Mfgr.. 
45C " " . 



3.30 
1.60 
1.50 
1.50 



1.40 

4.41 

80 

80 



.31 
.25 
.25 
.45 



.20 
.20 



.40 
.35 
.40 
.40 



012 
012 
03 
03 



.028 
.013 
.035 
.035 



155,000 
185,000 
130,000 
180,000 



132,000 
160,000 
100,000 
140,000 



38 

14 

12 

8 



16 
48 
30 
20 



264. Manganese Steel. The addition of ferro-manganese to 
iron or steel produces manganese steel, the carbon content of 
which is of considerable proportion, being incidental and almost 
unavoidable rather than intentional. Manganese, like carbon, 
is a true hardener. 

The following table is indicative of the peculiar properties 
which manganese gives to steel: 

0% to H% Little or no appreciable effect if carbon content be low. 

2}%to6i% Strength and ductility diminish while hardness increases: 

remarkably brittle when cold, even with low carbon 

content. 
4i %to 6% With a carbon content of but .37% is reported to be so 

extremely brittle that it can be powdered under a hammer 

when cold and is ductile when hot. 
6i% to 8% Strength and ductility are increased while the magnetic 

quality decreases. 
10% Is very ductile and if not tough may be improved by water 

quenching. Strength equals that of crucible steel; it is 

too hard to file. 
12% Lineham says this metal is entirely lacking in strength no 

matter what the treatment, but the strength returns in 

its maximum at 14%. Relating nothing regarding the 

12% content, Howe states that as the proportion of this 

element rises above 6%, the strength and ductility both 

increase while the hardness diminishes slightly. 

13% It is practically non-magnetic. 

14% The maximum of both strength and ductility is reached. 

With this proportion the metal is so hard that it is difficult 

to cut with steel tools. 



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MATERIALS 31 

15% to 17% The ductility falls off abruptly, the strength remaining 

nearly a constant. 
18% Strength diminishes suddenly. 

Manganese steel is quite free from blowholes, is strong, ductile 
and hard, more fluid than cast steel, but pipes badly and when 
cast requires large feeding gates. It is difficult to mold on ac- 
count of its having a shrinkage of ^ inch per foot. It welds with 
great difficulty and its toughness may be increased by quenching 
from a yellow heat. Its enormous electric resistance is almost 
constant with changing temperatures and it is low in thermal 
conductivity. Such a remarkable combination of qualities, of 
great hardness which refuses to be diminished by annealing, a 
high tensile strength with astonishing toughness and ductility, 
combined with its non-magnetic qualities, would make this the 
ideal metal but for the fact that its hardness prevents its being 
machined or fitted by any but abrasive processes. 

In its ability to resist wear, manganese steel is the most 
durable metal known for hardness, toughness and malleability. 
It is suitable for steam shovel teeth, dredge pins, plow points, 
fine rails, frogs, switches and crossings, crushing rolls for ore, 
rock screens, gear sprockets, or anything where a grinding wear 
in dust is required. The best composition is manganese from 
12% to 15%; carbon not over .5%; phosphorus not more than 
.4%; and sulphur not more than .4%. Manganese castings 
should always be annealed. 

265. Silicon SteeL Metcalf makes the following trite remarks 
concerning silicon steel: ''Steel containing 3% of silicon has 
been put upon the market and great claims made for it. It is 
exceedingly fine-grained and hardens very hard; it is brittle, 
much more liable to crack in hardening than ordinary steel and 
it is not nearly so strong as carbon steel . . . altogether, then, 
silicon steel is expensive and it presents no very good qualities 
in compensation." 

266. Tungsten or Mushet Steel. Tungsten or self-hardening 
steel is a special cast steel — an alloy of iron, carbon, tungsten 
and manganese, some brands of which contain chromium. It 
was erroneously supposed for a long time that tungsten was the 
metal that gave to this alloy its peculiar properties; however, it 
is now conclusively proven that the manganese together with 
carbon are the hardeners and that chromimn improves the quality 



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32 ENGINEERING AND SHOP PRACTICE 

of the steel. It is not to be inferred that tungsten is an unneces- 
sary constituent for it plays an important part as the mordant 
by which the alloy produced contains a larger combined carbon 
content. This steel retains its hardness almost up to a red heat. 

Regular tungsten steels contain from 5i% to 10% of tungsten. 
Professor Langley remarks in this connection: **I have made 
steel containing as high as 25% tungsten and very little carbon 
which was so soft that it could be readily touched with a file.*' 
Had the good professor accidentally burned a tool of this steel, 
as was done by the careless smith during the Taylor-White 
experiments, and then tried to see just what work it would do, 
in all probability we would have had our high-speed steels some 
twenty years sooner. 

Tungsten steel is more widely known as self-hardening or 
air-hardening steel, from its property of hardening when allowed 
to cool in quiet air. It is so hard in its ordinary condition that 
it cannot be machined and, like all steels of this class, has to be 
forged to the desired shape. Self-hardening steel tools are 
essentially roughing tools, other brands of steel proving more 
efficient for finishing. Its hardness is not improved by the 
ordinary tempering; it may be annealed, however, by keeping 
it at an orange heat for from 24 to 36 hours and allowing it to 
cool, imbedded in the furnace in hot sand or ashes for the same 
length of time; it may then be machined. Its chief use is for 
cutting tools. 

Perhaps it will be of interest to note that of ten samples of 
the celebrated Damascus steel of the Orient analyzed by Due de 
Luynes, eight contained tungsten, two of them in quantities of 
.52% to 1.% and all samples contained nickel, some as high 
as 4%. 

267. Vanadium and Chrome Vanadiimi Steels. As has been 
previously noted, vanadium bids fair to become a rival of carbon 
in its ability to produce great changes in steel by the addition 
of very small percentages. Vanadium has a tendency to cause 
brittleness. E. F. Lake, reporting on this alloy steel, states that 
it compares favorably in static strength with any of the steels 
and that it exceeds all others in its ability to resist dynamic 
stresses. An instance is given by another steel man where the 
addition of .25% of vanadium increased the tensile strength of 
a carbon manganese steel 65%, while the elastic limit was in- 



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MATERIALS 33 

creased 68%. This alloy of carbon, manganese and vanadium, 
with an addition of 3.34% of nickel, had its tensile strength 
increased 61% from 94,528 to 152,531; while the elastic limit 
was raised 64% to 112,539 with an elongation of 26%. 

On accomit of its brittleness, vanadium steel should always 
be annealed, and when annealed at about 1475 degrees and oil- 
tempered, as will be seen from the tables given below, some 
remarkable properties are patent. The composition of the steel 
tabulated is as follows: 

Vanadium, .17%; Chromium, 1.%; Carbon, .25%,; Manganese, 
.5%. 



Tensile Strength 
Lbs. Per Sq. In. 



Elastic Limit 
Lbs. Per Sq. In. 



Elongation 
in a" 



Reduction 
of Area 



The best high-speed cutting steel produced by Taylor-White 
to this date (1907) has a vanadium content of .29%. 

268. Aluminum, Cobalt, Tin, Titanium and Other Steels. 
Aluminum^ Cobalt, Tin and Titanium, As will be gathered from a 
reading of Sect. 218, there is nothing in the mechanical properties 
of these four steels which would lead any one to make a preference 
in their favor. The small percentage of aluminum which re- 
mains in the steels, not passing off in the slag, up to a content of 
.5% , increases the tensile strength and raises the elastic limit, but 
the elongation and reduction of area are materially injured. 

Kent classes the action of aluminum along with tha^ of silicon, 
sulphur, phosphorus and copper as giving no increase to the 
hardness of iron, in contradistinction to carbon, manganese, 
chromium, tungsten and nickel. Aluminum seems to combine 
in itself the advantages of both silicon and manganese, but so 
long as alloys containing these metals are so cheap and aluminum 
so dear, its extensive use seems hardly probable. 



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ENGINEERING AND SHOP PRACTICE 



Other Steels. Invar is the name given to a metal which is a 
non-expanding nickel steel, having an approximate composition 
of 64% iron, 35% nickel and the remaining 1% made up of 
carbon, silicon, manganese, etc. Because it is non-expanding. 
Invar has been found to be exceedingly valuable in the construc- 
tion of scientific instruments. 

Resista steel, so called, has a chemical composition of 79% 
iron, 6% manganese, 15% nickel and a tensile strength of 68 
tons, with an elongation of from 50% to 70%. 

269. High-speed Cutting Tool Alloys. As indicating the four 
epochs in the history of tool steels, the carbon tool steel era; 
the self-hardening steel era; the discovery of high-speed tools; 
and modem high-speed tools, the following table, taken from 
President Taylor's monumental A. S, M. E. address, on the 
Art of Cutting Metals, is given. 

The table gives the chemical analysis of four steels which are 
typical of the various eras in the development of metal-cutting 
tools. 



MakeofSted 



Jessup 

Mushet, Self Hardening, 

Tungsten 

Original Taylor-White 
Best Modem High Speed 

Taylor-White 



& 



5.441 
8.00 

18.91 



0.207 

0.398 
3.80 

5.47 



I 

5 



& 



1.047 



s. 



0.189 



.015 1.578 
1.85 0.30 



0.67 



0.11 



0.29 



0.206 

1.044 
0.15 

0.043 



I 



0.017 0.017 



0.025 



0.030 



ii 



l5 



16 

26 

58 to 

61 

99 



The chemical composition of the medium steel forging used 
for these cutting tests is as follows: 

Carbon, 0.34%; Manganese, 0.54%; Silicon, 1.769c; Phos- 
phorus, 0.037%; Sulphur, 0.026%,; Tensile Strength, 70,280 
pounds; Elastic Limit, 34,630 pounds.; Angle of tools used on 
medium steel forgings, Clearance Angle, 6 degrees; Back Slope 
8 and Side-Slope 14 degrees. 



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Steel, Manipulation 

271. Steel Castings. Steel castings, similar to iion castings, may 
now be made in almost any desired shape; the greatest difficulty 
having been experienced in the production of suitable molds 
rather than in the handling of the material. The open-hearth 
steel is considered superior to the Bessemer for this class of work. 

272. Structure. As we have already learned, steel is a chem- 
ical compound of iron and carbon generally containing some 
other elements as silicon, sulphur, phosphorus, manganese, etc. It 
contains no free or graphitic carbon as does cast iron; its tensile 
strength is greater than wrought iron and its compressive strength 
though less than cast iron is greater than wrought iron. The 
strength of steel varies greatly with its purity and the amount 
of carbon which it contains. Unlike wrought iron it is fusible, 
unlike cast iron it can be forged; and with the exception of very 
low grades, possesses the valuable quality of hardening when 
suddenly cooled from a proper temperature. From the matter 
in the early part of the subject, we discover that steel is made in 
one of the three following ways: 1, by adding carbon to wrought 
iron; 2, by removing carbon from cast iron; 3, by melting together 
cast and wrought iron in suitable proportions. 

273. Treatment. The accompanying table (Fig. 273), illus- 
trating the effect produced by various processes of working, is 
compiled from data obtained by Professor J. W. Langley. 



B 



I 



Cold-hammered 
Bar 

Bar Drawn 
Black. 

Bar Annealed 

Bar Hardened 
and Drawn 
Black .... 



153 

75 
175 



30 



Carbon 



1.25 

1.25 
1.31 



1.09 



.47 

.47 
.70 



.36 



I 



.575 

.577 
.580 



.578 



I-' 



92,420 

114,700 
68,110 



152,800 



& 






141,500 

138,400 
98,410 



248,700 



s. 



2.00 

6.00 
10.00 



8.33 



I 

(4 



2.42 

12.45 
11.69 



17.9 



Fig. 273. 



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36 ENGINEERING AND SHOP PRACTICE 

The total carbon given in the table was found by the color 
test, which is affected, not only by the total carbon, but by the 
condition of the carbon. 

The analysis of this steel is: 

Silicon 242 Manganese 24 

Phosphorus 02 Carbon (true total car- 
Sulphur 009 bon by combustion) . 1.31 

Note. Both the Bessemer and open-hearth processes are 
used for the production of structural steel; however, according 
to Metcalf, for fine boiler plates, armor plates and gun parts, 
open-hearth steel has won its place as completely as has the 
crucible for fine tool steels, or the Bessemer for rails. 

274. Working. Great care should be exercised in working 
steel, as costly materials may be rendered useless by improper 
handling on the part of the operator; the defects thus easily 
caused are overheating, burning and checking. In general use a 
very gentle blast with a good body of fuel, and forge at as low 
a heat as possible. Harden at a low cherry red — 1450° to 
1500° Fahr. Light, rapid blows with the hammer as the color 
is dying out have a peculiarly beneficial effect on the grain of 
the piece so treated; this is called *' hammer refining." 

275. Theory of Hardening. As other elements, such as small 
quantities of manganese, silicon, phosphorus and sulphur appear 
in carbon steel rather as incidental than intentional contents, we 
may neglect the others and concern ourselves with carbon as 
the true hardener. Broadly speaking, carbon may exist in the 
steel in either of two forms or states; viz., as cement ite, which 
Mr. Taylor calls *^ hardening carbon," or as pearlite, termed 
*' softening carbon." In the annealed bar as it is received from 
the dealer, the carbon exists as pearlite or ** softening carbon." 
Before the steel can become hard, the pearlite must change to 
the *' hardening carbon," cementite. The change is effected by 
heating the steel through a certain range of temperatures which 
have been determined by scientists and which conform closely 
to the following description: 

It is a matter of general knowledge that to harden steel it 
must be heated to what is empirically known as a low '* cherry 
red," a temperature close to 1450° F. When the temperature 
passes slightly above 1450° F. the pearlite is entirely changed to 



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MATERIALS 37 

cementite; provided a certain short interval of time be allowed 
for the process because it takes time to effect the change. If the 
temperature is allowed to drop below 1400° F. the cementite 
will change back to pearlite; i.e. from ** hardening" to ''softening 
carbon," and the change may be made over and over again. 

The fact that it takes a certain appreciable time for the change 
to take place enables us by quenching to hold or arrest this 
transformation at any desired point. If a tool heated above 
1450® be rapidly and continuously cooled, by quenching in water 
or otherwise, down below a temperature of 392° F., the cementite 
or "hardening carbon" will not have had time to change to 
pearlite or ** softening carbon" and will remain trapped in the 
steel, as it were, in its hard or diamond-like form. The trapped 
cementite gives to the whole tool its hardness, and so long as the 
temperature remains below 392° F. it cannot be changed back 
to pearlite. Tools hardened in the above manner are generally 
too hard and brittle to be used for ordinary machine shop work 
and have to be tempered or softened. If we had stopped the 
process of cooling at any point between 1450° and 392°, even 
for a comparatively short time, then to a greater or less degree 
the change, from cementite to pearlite would have taken place 
and the tool would have been softer and less brittle. If, now, 
after having cooled the tool rapidly from 1450° down below 
392° F., we reheat it to some point above 392° and below 600° F., 
the change from cementite to pearlite begins to take place, the 
tool becoming softer and softer until 600° is reached, when it 
will be found entirely soft and the cementite changed to pearlite. 

With the aid of a Le Chatelier pyrometer, it was discovered 
that as the carbon changed from cementite to pearlite, so definite 
and powerful was the molecular change in the structure of the 
steel, that the heat developed was sufficient to hold or even raise 
the temperature slightly. This occurs at 1400° F. and it was 
for this reason that this point became known as the "reheating 
point," " recalescence point " or " critical point." " All tool steels, 
whether carbon or high speed, have at least one critical point," says 
Mr. Taylor, "and many of them have two or more in cooling from 
a high heat to the normal temperature of the air." At every 
critical point, then, some internal molecular change takes place. 

The lower critical point of carbon tool steel, at which point 
softening or tempering takes place, broadly speaking, lies some- 



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38 



ENGINEERING AND SHOP PRACTICE 



where between 392® and 600° F.; and the upper critical point 
occurs about 1450° F. when the change from pearlite to cemen- 
tite takes place. It is important to know that the critical points 
do not occur at the same temperatures when cooling; — i.e. 
when the heat is going down — as when heating — i.e. when the 



1200 


































ism 


UOO 








/ 


























iifa£ 








/ 




C< 


OllDj 


rand 


Hea 


ting 


Cl^^^ 


es 










UOOO 
















Ord 


aao 


Car 


^on 










/ 


1308* 


















St 


jel 












/ 


900 








I 






















/ 


r 


loss" 






885 




B25r 




















/ 














1 


\ 


















/ 


/ 




1473" 


800 










\ 














7iM 


c< 

700( 


> 


OF 

iWi 




700 










\ 


\ 


^ Ul€ 


"f 










( 


1 






1298" 










G8i 


^C^ 










^^ 




/ 








000 












X 




' ' 








/ 








iiu" 










J 


/ 












J 


/ 


















/ 
























838° 


600 










^Pro 


tM.C 
Ooo 


JI.CI 
insC 


rpent 
arve 


er*8 
















400 










A 

Dlft 


ctaal 
rentli 


yplo 
IGal 


ranor 


r 

icter 






1 










708° 
























A 
Hea 


?rolM 
tiilg< 


Jurv« 
























1 


is'c* 




eoo'f 










578** 


8G0 




















/ 














800 


















/ 




F 












838° 



Fig. 275a. — Carbon Steel Curves. 

heat is going upward — indicating that the internal changes 
occur at different temperatures. See Fig. 275a. 

By a comparison of Mr. Taylor's curves herewith, Fig. 2756, 
it will be noted that the principal critical point in heating is 
higher by about 160° F. than the principal critical point in the 
cooling, and therefore the operator who is hardening carbon 



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MATERIALS 



39 



steel is much more interested in the heating than in the cooling 
curve, as it is to the former he must look for a point just above 

Temperature, Centigrade 

o § 8 § k i i i 




e g i § 



i i i § i i i 

or? o o o o 

Teiuperature, Falirenheit 



which he must heat his tool in order that it may harden thor- 
oughly, preserve a fine grain and be free from the brittleness and 
other troubles which come from the overheating. 



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ENGINEERING AND SHOP PRACTICE 



276. Hardening and Tempering. When a clean piece of steel , 
hardened or unhardened, is exposed to heat in air it will assume 
different colors as the heat increases. It is a well-established fact 
that these colors are due to thin films of oxide that are formed as 
the heat progresses. These colors are as useful as beautiful and 
furnish an unvarying guide, with a given grade of steel, as to the 
condition of the hardened tool. Tempering steel is the act of giv- 
ing it, after it has been shaped, the hardness necessary for the 
work it has to do. In most cases this is done by first hardening 
the piece, generally a great deal harder than is necessary, by sud- 
denly cooling from a low cherry heat 1450° to 1500° Fahr. and 
then toughening it by slow heating and gradual softening until it is 
just right for the work it has to perform. A modification of this 
latter process consists in hardening the cutting portion of the tool 
by a momentary chilling, and then allowing the still heated por- 
tion to raise the temperature of the chilled and hardened portion 
to the desired point, when further rise is prevented by a sudden 
quenching. The word temper, when applied to steel, has, unfor- 
tunately, two diverse meanings. The steel manufacturer uses the 
word to designate the amount of carbon which steel contains; 
and the worker the color of the oxide at a given temperature. 

277. Table of Tempering Data. 



Manufactdker's and Purchaser's Data 


§ 




Worker's Data 


1 

2 

1 


•a 


lii 


n 


a 
Is 

II 

is 


1! 
Ill 


u 


w 


^ 


H 


is 


H 


H 



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MATERIALS 
277. Table of Tempering Data (continued). 



41 



Manufacturer's and Purchaser's Data 



I 

•3 



I' 

-He 



I 



Worker's Data 



&M 



1^ 



a 



ii 



Bears heat 
not above 
cherry red 
ness; great 
care is re- 
quired in 
working. 



Screw cutting dies, 
chisels, punches, 
and milling cut- 
ters. 



115 



Cold chisels, punch- 
es, dies, large 
taps, and milling 
cutters and small 
shear knives. 



105 



High 



Straw 



460 



Milling cutters, 
lathe tools, 
taps, dies, 
reamers, 
punches and 
dies, hammer 
faces, drills. 



Easily 
burned, re- 
quires skil- 
ful manip- 
ulation in 
working. 



Large punches 
shear blades, large 
dies, and some 
blacksmith's 
tools. 



05 



Stamping dies, 
hammers, cold 
sets, track chisels 
and blacksmith's 
tools. 

Lathe, planer and 
machinist's tools. 



High 
Medi- 
um 



Brown 



490 



Cold chisels, 
drills, drifts 
and brass 
working tools, 
shear knives. 



85 



A good com- 
mon tool 
steel. 



Lathe, planer and 
machinist's tools. 

Swages, flatters, 
cupping tools and 
blacksmith tools 
generally. 



75 



Medi 
um 



Brown- 
ish 
Purple 



540 



Cold chisels, 
some hack 
saws, wood- 
working tools. 



Works some- 
what like 
wro. iron 



Tires, etc. 



60 
to 
45 



Mild 



Dark 
Blue 



570 



Tempers 
slightly. 



Boiler Plates and 
axles. 



35 
to 
20 



Low 



Pale 
Blue 



610 



Springs, fine 
saws. 

Common saws, 
some springy. 



Does not 
temper. 



Some machine 
parts 



Below 
20 



Soft 



Green- 
ish Blue 



630 



Too soft to be 
useful. 



Fig. 277. 



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42 ENGINEERING AND SHOP PRACTICE 

Note, The uses given for temper colors and the other data 
in the above table are to be taken as merely giving a good general 
idea; experienced men are guided by results, and select and tem- 
per in the way that gives these results. 

The tensile strength of steel varies from 46,800 pounds to 
248,700 pounds per square inch. 

100 carbon steel, i.e, steel containing 1% carbon, is the 
strongest in every way, as this percentage is about the saturation 
limit. 

278. The Taylor-White Treatment of Tool Steels. Mr. Taylor 
says, referring to their invention: "By far the most important of 
the discoveries made by us, and that which led to the modem 
high-speed tools, was the discovery that when tools made from 
tool steel, old in its chemical composition (containing not less 
than .5% of chromium and not less than 1% of tungsten, or its 
equivalent), were treated in a new and completely revolutionary 
manner to an extraordinarily high heat — a heat so high that it 
would have utterly ruined ordinary tools — this treatment im- 
parted an entirely new property or quality to a cutting tool; 
viz., the property called "red hardness.*' And it is this new 
property which enables these tools to run at their high cutting 
speeds. 

The treatment is described as follows: The first or high heat 
treatment consists of heating the tool, 

(a) Slowly to 1500° F. 

(6 ) Rapidly from that temperature to just below the melting- 
point. 

(c) Cooling fast to below the breaking-down point; i.e. 
1550° F. 

{d ) Cooling either fast or slow from this point to the tempera- 
ture of the air. 

The second or low-heat treatment consists of heating the tool, 

(a) To a temperature below 1240°, preferably to 1150° for 
a period of about five minutes and 

(6) Cooling to the temperature of the air, either rapidly or 
slowly. 

Alloys, Bronzes, Brasses, etc. 

281. Properties and Characteristics. Alloys may be made of 
various metals that have an affinity for one another, and the 



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MATERIALS 43 

mixtures have properties and characteristics which neither of 
the metals possess. For instance, copper is a soft, red-colored, 
tenacious metal of brilliant luster; is malleable and ductile, and 
fuses at about 1930° F.; its tensile strength is from 20,000 to 
30,000 pounds per square inch. Tin, on the other hand, is a 
white, soft, lustrous metal, malleable and having but little 
strength; it fuses at 442° F., and has a tensile strength of 3500 
pounds per square inch. Two parts of copper will combine with 
one part of tin, forming a homogeneous compound that is gray 
in color, very hard and brittle. 

282. Bronzes, Copper-Tin Alloys. Alloys of copper and tin 
are known as bronzes. From 1% to 12% of tin increases the 
tensile strength of copper; from 1% to 8% increases the ductility, 
and from 1% to 18% the compressive strength. Greater quan- 
tities of tin render the metal very hard and brittle; so hard and 
brittle as to be of little use where strength is required. 

283. Phosphor Bronze. The addition of phosphor to copper 
alloys, deoxidizes the copper oxides, improving many of the 
alloys in strength, ductility and fluidity. In general, the grain 
of fracture of phosphor alloys is finer and the color brighter than 
others. A good phosphor bronze has a tensile strength of 52,000 
pounds, with an elongation of 8.4%; it contains 79% of copper, 
10% of lead, 10% of tin and 1% of phosphorus. Like ordinary 
bronzes, the strength of phosphor bronze varies according to the 
per cent of copper, tin, lead, zinc, etc., in the alloy. 

284. Brasses, Copper-Zinc Alloys. Strictly speaking, any 
alloy of copper and zinc is known as brass. Zinc assists in 
obtaining sounder castings by giving greater fluidity to the mix- 
ture, and proves an excellent deoxidizing agent for the copper. 
Zinc costing about one fourth as much as tin is used in the alloy 
wherever such castings will prove suitable. 

285. Copper-Tin-Zinc Alloys. By a combination of these 
metals a very remarkable metal was produced. A metal con- 
taining 55 parts of copper, .5 parts of tin, and 44.5 parts of zinc 
gave, in a test for transverse strength, 72,308 pounds as a modulus 
of rupture, with a deflection of 3.5; its tensile strength was 68,900 
pounds with an elongation of 9.43%. Professor Thurston made 
an ingenious cast to represent graphically the laws of variation 
of strength in these alloys. If one side of a triangle represent 
copper, a second tin and a third zinc, the vertex opposite 



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44 ENGINEERING AND SHOP PRACTICE 

each of these sides represents 100 of each element respectively. 
On points in a triangle of wood, representing different alloys 
tested, wires were erected of lengths proportional to the tensile 
strength, and the triangle then built up of plaster to the height 
of the wires. The surface thus formed has a characteristic 
topography, representing the variations of strength with varia- 
tions of composition. The highest point obtained was a compo- 
sition of 55 copper, zinc 43 and tin 2, with a tensile strength of 
70,000 pounds. The formula for the strongest of these alloys is: 

Zinc + (3 X Tin) = 55. 

Illustrating the formula by choosing 7 for the Zinc, we 
have 

7 -f 3 T = 55 

3T = 55-7 = 48 
T = 16 

and our composition becomes 

7 Zinc, 16 Tin and 77 Copper 
i.e. 7+16 + 77 = 100% 

The formula Zinc + 4 Tin = 50 gives a series of alloys having 
greater ductility together with considerable strength, which may 
be more easily worked by machine tools; the other series being 
generally too hard for ordinary machinery. 

286. Lead, Use in Alloys. Lead, though having but little 
affinity for either copper or zinc, is added to assist in giving to 
the castings a smooth surface; it is also used on account of its 
cheapness. Should the lead in copper and zinc alloys exceed 3% 
of the mixture, the result will prove unsatisfactory. Lead 
alloyed with arsenic is used for making shot, with bismuth for 
fusible alloys, and with antimony for type metal. 

287. Composition of 26 Ordinary Commercial Alloys. In 
the table below (Fig. 287o) is given the chemical composition 
of the ordinary alloys in every-day use in brass foundries. The 
table is taken from the American Machinist. 



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MATERIALS 



45 



Name of Metal 


1^ 


Zinc 
Lbs. 

6 


Tin 
Lbs. 

8 


Lead 

LlM. 


Use of Metal 


Admiralty Metal . . 


87 





For parts of engines on board 












naval vessels. 


Bell Metal 


16 


— 


4 


— 


Bells for ships and factories. 


Brass (YeUow) . . . 


16 


8 


— 


i 


For plumbers, ship and house 
brass work. 


Bush Metal 


64 


8 


4 


4 


For bearing bushes for shaft- 
ing. 


Gun Metal 


32 


1 


3 


— 


For pumps and other hy- 
draulic purposes. 


Steam Metal 


20 


1 


H 


1 


Castings subjected to steam 
pressure. 


Hard Gun Metal . . 


16 


— 


2J 


— 


For heavy bearings. 


Muntz Metal 


60 


40 






Metal from which bolts and 
nuts arc forged, valve 
spindles, etc. 


Phosphor Bronze . . 


92 


— 


8pho 


8. tin 


For valves, pumps and gen- 
eral work. 


Phosphor Bronze . . 


90 




lOphc 


)s. tin 


For cog and worm wheels, 
bushes, axle bearings, slide 
valves, etc. 


Brazing Metal 


16 


3 


— 


— 


Flanges for copper pipes. 


Brazing Solder 


50 


50 


— 


— 


Solder for the above flanges. 



Fig. 287a. 

In this Table (Fig. 2876 ) is given the composition of various 
other useful alloys. This table is from Kent, and is gleaned from 
various sources: 



Alloy 



U. S. Navy Dept., Journal Boxes 

and Guide-Gibs 

Tobin Bronze 

Naval Brass 

Composition, U. S. Navy 

Brass Bearings (J. Rose) 

Gun Metal 



Copper 



6 
82.8 
58.22 
62 
88 
64 
87.7 
92.5 
91 

87.75 
85 
83 
13 



Tin 



1 
13.8 

2.30 

1 
10 

8 
11.0 

5 

7 

9.75 

5 

2 

2 



Zinc 


Lead 


i 





3.4 


— 


39.48 


— 


37 


— 


2 


— 


1 


— 


1.3 


— 


2.5 


— 


2 


— 


2.5 


— 


10 


— 


15 


— 


2 


— 



Anti- 
mony 


Remarks 


_ 


P&rts 


— 


Per Cent. 

it 


_ 


n 





tt 


— 


FSLTis 


— 


Pfer Cent. 





tt 





tt 


__ 


tt 





It 





tt 


— 


Parts 



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46 



ENGINEERING AND SHOP PRACTICE 
Fig. 287& {continued). 



Alloy 



Copper 


Tin 


Zinc 


Lead 


Anti- 
mony 


76.5 


11.6 


11.7 


— 


— 


82 


16 


2 


— 


— 


83 


15 


1.5 


0.5 





20 


1 


1 


1 


— 


87 


4.4 


4.3 


4.3 




88 


10 


2 


— 


— 


84 


14 


2 








80 


18 


— 


— 


2.0 


81 


17 


— 


— 


2.0 



Remains 



Tough Brass for Engines 

Bronze for Rod Boxes (Lafond) 

Slightly Malleable 

Bronze for Pieces Subject to 

Shock 

Red Brass 

Bronze for Pump Casings (La 
fond) 

Bronze for Eccentric Straps (La- 
fond) 

Bronze for Shrill Whistles 

Bronze for Low-toned Whistles . 



— Per Cent. 



Parts 
Per Cent. 



Fia, 2876. 

288. Telephone and Telegraph Wire Alloys. Silicon bronze, 
made of 97 parts of copper and 3 parts silicon, has a tensile 
strength when in a casting of about 55,000 pounds to the square 
inch, with an elongation of from 50% to 60%. 

This table gives a comparison of copper, silicon-bronze and 
phosphor-bronze drawn wires and is taken from Engineering. 



Description of Wire 



Pure Copper 

Silicon Bronze (telegraph) . . . 
Silicon Bronze (telephone) . . . 
Phosphor Bronze (telephone) . 



Tensile Strength 



39,827 Lbs. per sq. in. 

41,696 " " " " 
108,080 " " " " 
102,390 " " " " 



Relative ConductiWty 



100 per cent. 
96 " 
34 " 
26 " 



Fig. 288. 

Alloys; Solders, Bearing Metal and Other Well Known 

Alloys 

291. Solders. Common Solder. Common solder is an alloy of 
equal parts of tin and lead. Fine solder contains 2 parts of tin 
to 1 of lead, while cheap solder contains 2 parts of lead to 1 of 
tin. These solders fuse at a temperature of about 370° F. 



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MATERIALS 47 

Common Pewter. Common pewter contains 4 parts of lead 
to 1 of tin. 

Gold Solder. Gold solder contains 14 parts of gold, 6 parts 
of silver, and 4 of copper. 

SUver Solder. Silver solder contains 70 parts of yellow brass, 
Hi parts of tin and 7 parts of zinc. 

German Silver Solder. German silver solder contains 38 parts 
of copper, 54 of zinc and 8 of nickel. 

292. Bearing Metal Alloys — Babbitt Metal. The well-known 
Babbitt metal contains approximately 50 parts of tin, 2 parts of 
copper and 4 parts of antimony. An excellent white metal alloy 
contains 55 parts of tin, 18 of antimony, 23^ of lead and 3^ of 
copper. The principal constituents of most bearing metals are 
copper, tin, lead, zinc, antimony, iron and aluminum. 

293. Composition of 24 Bearing Metal Alloys. The table on 
page 49 (Fig. 293) gives the constituents of 24 of the most im- 
portant bearing metals as analyzed in the Pennsylvania Railroad 
laboratory at Altoona: 

294. Gurley*s Bronze. Gurley's bronze is used for the frame 
work of engineer's transits, etc., and is composed, according to 
W. J. Keep, of 16 parts of copper, 1 of tin, 1 of zinc, i of lead, 
and has a tensile strength of 41,000 pounds. 

295. German Silver. German silver is an alloy containing 
about 51.1 copper, 13.8 nickel, 3.2 tin and 31.9 zinc. 

296. Aluminum Bronze. Aluminum bronze, an alloy of 90% 
copper and 10% aluminum, produces a remarkably tenacious 
metal, with a tensile strength varying from 75,000 to 90,000 
pounds per square inch, with from 4% to 14% elongation. 

297. Manganese Bronze. Manganese bronze is in reality a 
manganese brass, for zinc, instead of tin, is the chief element 
added to the copper. 

The manganese existing in these alloys extends from a trace 
up to 5%; manganese may be mixed with copper to give a metal 
that may be forged. Its chief use, on account of its strength 
and ductility, is for propeller blade castings, although sheets of 
manganese bronze are used to a large extent, for mining screens, 
on account of their non-corrosive qualities. 

Manganese bronze has a tensile strength of about 60,000 
pounds per square inch; when rolled, however, its tensile strength 
reaches from 95,000 to 106,000 pounds per square inch. Many 



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48 ENGINEERING AND SHOP PRACTICE 

of the manganese bronzes on the market contain no manganese 
whatever. 

298. Pewter and Type Metal. Pewter is an alloy contain- 
ing copper, tin and antimony. A hard pewter is composed of 
2 parts of copper, 96 of tin, and 8 of antimony; should the 
copper be increased a softer pewter would result. Common 
pewter contains 4 parts of lead to 1 part of tin. 

Type metal is an alloy containing from 4 to 5 parts of lead 
to 1 of antimony. 

299. Fusible Alloys« Bismuth is the chief element which 
gives the fusible alloys their low melting-point. Fusible alloys 
can be made by various compositions of lead, tin, bismuth and 
sometimes cadmium, with a melting-point of from 149° to 475° F. 
An alloy of 1 part lead, 3 parts tin, and 5 parts bismuth melts 
at 212° F. Alloys of bismuth have been used for making fusible 
plugs for boilers, but according to Kent, it is found that they 
are altered by the continued action of heat so that one cannot 
rely upon them to melt at the proper temperature. 

Pure Banca tin is used by the United States Government for 
fusible plugs. 



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MATERIALS 



49 



Analysis of Bearinq Metal Allots 



Me<al 



Copper 


Tin 


Lead 


Zinc 


Antimony 


75.47 


9.72 


14.57 


_ 


_ 


77.83 


9.60 


12.40 


trace 


— 


59.00 


2.16 


0.31 


38.40 


— 


75.80 


9.20 


15.06 


— 


— 


76.41 


10.60 


12.52 


— 


— 


90.52 


9.58 


— 


— 


— 


55.73 


0.97 


— 


42.67 


— 


79.17 


10.22 


9.61 


— 


— 


70.20 


4.25 


14.75 


10.20 


— 


— 


— 


87.92 


— 


12.08 


92.39 


2.37 


5.10 


— 


— 


trace 


— 


83.55 


trace 


16.45 


81.24 


10.98 


7.27 


— 


— 


— 


— 


84.33 


trace 


14.38 


76.80 


8.00 


15.00 


— 


— 


1.60 


98.13 


— 


— 


— 


— 


— 


88.32 


— 


11.93 


4.01 


9.91 


1.15 


87.57 


— 


— 


— 


78.44 


0.98 


19.60 


— 


trace 


84.87 


— 


15.10 


— 


14.38 


67.73 


— 


16.73 


— 


— 


80.69 


— 


18.83 


— 


— 


94.40 


— 


6.03 



Iron 



Carbon Bronze 

'i Gomifih Bronze 

Tobin Bronze 

Graney Bronze 

Damascus Bronze 

Manganese Bronze . . . 
Harrington Bronze . . . 

Hiosphor Bronze 

Oannelia Metal 

White Metal 

Delta Metal 

Magnolia Metal 

A jax Metal 

Cai^box Metal 

Ex. B. Metal 

Anti-friction Metal (No. 1) 
Anti-friction Metal (No. 2) 

Salgee Anti-friction 

American Anti-friction. . 

GaivBrass Lining 

Graphite Bearing Metal. 

Antimonial Lead 

Hard Lead 



Other Constituents: 
1 No graphite. 
* Possible trace of carbon. 
'Trace of phosphorus. 

^(Torrey says this metal always contains tin.) 
Possible trace of bismuth. 

Fig. 293. 



trace* 
0.11 



0.68 

7 

0.55 

0.07 
trace* 

e 

0.61 

8 

trace 



0.65 



*No manganese. 

A Phosphorus or arsenic. 

7 Phosphorus. 0.94. 

8 Phosphorus. 0.20. 



0.37. 



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CHAPTER III 

FRICTION, LUBRICANTS AND LUBRICATION 

Friction and Lost Work 

311, Friction. The surface of every solid, no matter how 
highly polished, on being observed through a microscope, has in 
it little elevations and depressions. When two surfaces are 
placed together the elevations of one tend to fill the depressions 
of the other and thus offer resistance to movement; it is this 
resistance that is termed friction. The work of smoothing or 
breaking off the interlocking points produces heat. 

Friction is detrimental for the reasons: (1 ) that it takes power, 
(2) produces heat, (3) produces wear, and (4) is the cause of 
much trouble, the trouble arising in most cases from the increase 
in temperature and ensuing expansion. The only difference, then, 
that may exist between a bearing that gives trouble and one that 
does not may be in its conduction, rather than its production, of 
heat. The amount of power consumed in overcoming friction is 
astonishing to one unfamiliar with the subject and is estimated 
by various authorities to be from 40% to 80% of the fuel con- 
sumed. 

312. Friction Reduction. If we interpose between two sur- 
faces a film of oil, we discover that though they slide more easily 
they still offer some resistance to movement. This thin film of 
oil holds the surfaces apart, lifting the irregularities of the one 
free from those of the other, the remaining friction being that in 
the oil itself, there being no friction here of metal on metal, 
because they are not in contact. Examining the conditions which 
obtain in the ordinary bearing in operation, we find that the oil 
next the shaft moves with it while that on the bearing moves 
very slowly. The slower moving portion of the film has a re- 
tarding effect on the faster-moving portion and thus produces 
friction in the oil itself. Grossman discussing these conditions 
states that: *' Different parts of the same lubricating layer, moving 

50 



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FRICTION, LUBRICANTS AND LUBRICATION 51 

at different speeds, produce relative movements which result in 
friction in the lubricant itself. Movement of the solid surfaces 
over the slower moving fluid particles produces friction between 
the solid and the liquid bodies, and consequently the frictional 
resistance of well lubricated solid bodies consists of the sum of 
the frictional resistance between the fluid and the solid bodies 
and between the particles of the fluid itself." 

It is clear from this, even to the veriest novice, that the thinner 
the oil the less internal friction it possesses and vice versa. The 
thinner the oil, however, the less ability it has of sustaining 
pressure, it being easily forced from the bearings under conditions 
of great pressure and high speed; while with the heavier oils of 
sufficient body to hold the surfaces apart, we have the greater 
internal friction. The temperature of a given oil, too, has much 
to do with its internal friction, for upon heating oils become 
thin and watery, and at still higher temperatures, on a surface 
where, when cold, we would expect oil to flow in a thin layer, we 
discover it to collect into minute globules which fly from the 
surface. For this reason it will be surmised that where excessive 
temperatures obtain, a solid lubricant such as graphite, talc, etc., 
must be used. 

313. Laws of Friction. From the foregoing paragraphs we 
conclude, as Professor Thurston points out, that where mixed 
friction (friction of metals and friction of oil) occurs, as is the 
case under ordinary conditions of lubrication, its laws approxi- 
mate those of solid friction as the bearing is run dry, and those 
of fluid friction as it is flooded with oil. Between these two 
extremes, solid and fluid friction, our coefficient of friction for a 
given condition must lie. 

314. Coeflicient oif Friction. The coefficient of friction of a 
body is the ratio of a force, required to slide it along a horizontal 
plane surface, to its weight. If a body of weight W is made to 
slide on a horizontal plane surface by a force F which pushes it 

F 
along with an uniform motion, the ratio -^ is called the coeffi- 
cient of friction. It is equivalent to the tangent of the angle of 
repose, which in turn is the angle of inclination to the horizontal 
of an inclined plane on which the body will just overcome its 
tendency to slide. This angle is generally designated by and 
the coefficient by /. 



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52 



ENGINEERING AND SHOP PRACTICE 



If we represent the vertically acting force of gravity by the 
line ab (Fig. 314), its effect in holding the body against the plane 
will be proportional to the line fee, and its effect in sliding the 
body down the plane will be proportional to the line ac, each 
of these lines being drawn in the direction in which its repre- 
sentative force acts. 

The quotient of the force tending to slide the body by the 
pressure between the sliding surfaces would be represented by 

QC 

r-. Now ac is the sine of the angle at &, and he is its cosine, and 

the quotient of the sine divided by the cosine is the tangent. 
Since the angle at a is common to both triangles, abc and abdj 




Fig. 314. 



and both have a right angle, the remaining angles at b and d, 
respectively, must be similar, and what is true of the angle at b 
is true of that at d or that of the plane. 

315. Solid Friction. With unlubricated solids sliding on one 
another / is practically a constant, dependent upon the nature of 
these surfaces, but independent of the area of contact of the 
pressure between the surfaces, and the velocity of rubbing. 

316. Fluid Friction. Thurston gives the following laws of 
fluid friction: For all fluids, whether liquid or gaseous, the re- 
sistance is: (1) independent of the pressure between the masses 
in contact; (2) directly proportional to the area of rubbing 
surface; (3) proportional to the square of the relative velocity 
at moderate and high speeds and to the velocity nearly at low 
speeds; (4) independent of the nature of the surfaces of the solid 
against which the stream may flow, but dependent to some extent 



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FRICTION, LUBRICANTS AND LUBRICATION 53 

upon -their degree of roughness; (5) proportional to the density 
of the fluid and related in some way to its viscosity. 

As has been previously stated it is somewhere between the 
two extremes, the solid and liquid friction, that we must look 
for our coefficient for any given bearing. 

Lubricants in General 

321. The Function of Lubricants. Lubricants are used pri- 
marily to reduce friction; however, in the machine shop, when 
used in connection with cutting tools, they perform another 
important function, that of dissipating the heat generated in 
making the cut. When used in this latter connection it is true 
that, while heat dissipation is the main function, the advantage 
as a lubricant must not be overlooked, and it is for this reason 
that lard oil is one of the best cutting oils. 

322. The Selection of Lubricants. So impoitant is the selec- 
tion of a lubricant for a given purpose that the profit or loss in a 
given manufacturing plant may depend upon it. A change of 
lubricant in one of the great cotton mills of Massachusetts effected 
a saving of 8i% of the coal, with an increase in the output of 
2%. It is for this reason that scientific investigation and labo- 
ratory tests should precede the selection of a lubricant for a given 
condition. Any of the great oil-refineries now gladly furnish 
certificates guaranteeing the physical qualities of their various 
brands of oils, so that the laboratory examination of oils from 
reputable concerns may be dispensed with unless adulteration is 
suspected, leaving only the trial of the various oils .to the pur- 
chaser. These merchants, and for that matter the manufacturers 
of solid lubricants as well, gladly assist in aiding their clients in 
such investigation by furnishing technical experts to supervise 
the tests. 

Oil Compounds and Adulterations 

331. Composition of Oils. It has been found by experiment 
that the best oil for lubricating bearings and other rubbing 
surfaces is invariably a pure mineral oil devoid of any vegetable 
or animal fat. The various factors, however, such as conditions 
of excessive pressure, speed, moisture, heat, cold and cost have 
led to the numerous brands which are usually mineral oils com- 



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54 ENGINEERING AND SHOP PRACTICE 

pounded with animal, vegetable and other ingredients to meet 
the various test requirements. 

332. Vegetable Oils. Vegetable oils possess few or no lubri- 
cating qualities of practical value, oxidize at comparatively low 
temperatures and have a disposition to become thick and 
gummy. 

333. Animal Oils. Animal oils, or carbohydrates, likewise 
tend to thicken and become gummy under the influence of heat 
and wear, and develop an objectionable acid which is sure to 
attack the metals with disastrous results. 

334. ParaflSne. Paraffine possesses few or no lubricating 
qualities and, aside from the production of a smooth surface, it 
is a resistant and retards the viscous action of an oil. It is used 
chiefly because it does not oxidize or evaporate readily. 

335. Wool Fat. Wool fat (degras), a common adulteration 
in cheap cylinder oils, is used to cut the gummy ingredients and 
to secure a better cold test. Its presence in an oil generally 
causes a thick deposit at the bottom of the barrel and results in 
the same charred deposit in the cylinder that occurs from the 
use of lump tallow. 

336. Objectionable Features. The presence of vegetable or 
animal oils, paraffine, resin, etc., tends to make an oil sticky 
and gummy, not only increasing the friction, but also rendering 
it efficient in the collection and accumulation of dirt. If it be 
necessary to compound an oil, pure, refined, acidless tallow oil, 
or pure, sweet, winter-strained lard oil should always be used. 

Lubricating Oils 

341. Qualifications of a Good Lubricant. Continued investi- 
gation and recent research indicate that the qualifications of a 
good lubricant are: (1 ) A minimum coefficient of friction — that 
which in bath lubrication most nearly approximates fluid friction. 
(2 ) Sufficient body to prevent the surfaces to which it is applied 
from coming in contact with each other under maximum pres- 
sure. (3 ) A maximum fluidity consistent with the body required. 
(4) A maximum conduction of heat. (5) A high temperature 
of decomposition, that is, high flash and burning points. (6 ) A 
freedom from corrosive acids of either mineral or animal origin. 
(7) A freedom from all materials which tend to produce oxidi- 
zation or gumming. (8 ) Its value, determined from the cost of 



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FRICTION, LUBRICANTS AND LUBRICATION 55 

consumption, cost of coal spent to overcome friction, and cost 
due to metallic wear. 

342. Oil Tests. An examination, in the determination of the 
above qualifications of the physical and chemical qualities of an 
oil, should proceed, according to Professor Stillman, in the fol- 
lowing order: (1 ) Identification of the oil, whether a simple 
mineral oil or animal oil, or a mixture; (2) density; (3) viscosity; 

(4) flash-point; (5) burning-point — fire test; (6) acidity; (7) 
coefficient of friction, and (8) cold test. 

343. Density of Gravity Test. The density or gravity test is 
made by means of an hydrometer and is an indication of vis- 
cosity, for the specific gravity of a particular petroleum oil 
increases as the viscosity increases. 

344. Viscosity or Fluidity Test. The viscosity or fluidity of 
an oil is determined by a viscosimeter and is usually expressed in 
the seconds of time in which a given quantity of oil will flow 
through an orifice, at a stated temperature. It is evident that, 
within the limits, the lower the viscosity of an oil (without too 
near an approach to metallic contact of the rubbing surfaces) 
the lower wall be the coefficient of friction. From this we note 
that each bearing would probably require an oil of a different 
viscosity, or that a slight change in a particular bearing would 
again change the requirements. 

345. Flash or Fire Test. The object of the flash and fire test 
in most instances is to insure the prevention of fire that might 
occur from the use of an oil giving off inflammable vapors; the 
higher the temperature under which the oil must work, the higher 
the fire test, so that it will not decompose or volatilize; though 
still, in the case of a cylinder oil, atomizing readily. Too high a 
fire test gives an oil that does not atomize readily enough to 
reach all the parts of the cylinder with the steam. The lowest 
ordinary fire test permissible is 300°. The flashing and burning 
points are determined by heating the oil in an open vessel, not 
less than 12° per minute, and applying the test flame every few 
degrees. 

346. Acidity Test. The object of the acidity test, as its name 
indicates, is the determination of the presence of injurious acids. 

347. Cold Test. The cold test is the determination of the 
temperature at which the oil will congeal, and must always be 
well below the conditions under which the oil operates. It is 



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56 ENGINEERING AND SHOP PRACTICE 

made by having an ounce of oil in a four-ounce sample bottle 
with a thermometer suspended in the oil, and exposing this to a 
freezing mixture of ice and salt; when the oil has become hard 
the bottle is removed from the freezing mixture and the frozen 
oil allowed to soften, being stirred and thoroughly mixed at the 
same time by means of the thermometer, until the mass will run 
from one end of the bottle to the other. The reading of the ther- 
mometer, when this is the case, is regarded as the cold test. This 
test is made for the purpose of determining whether or not the 
oil will feed freely without clogging through the lubricators. 

348. Oil Inspection. When it is necessary on account of the 
moisture, as in the case of a cylinder oil, to compound the straight 
mineral oil with a little animal oil, none but refined, acidless 
tallow oil should be used. 

The presence of paraffine — always highly objectionable — 
may be discovered by placing a bottle of oil on ice for fifteen 
minutes; if the oil becomes cloudy, it is an indication of paraffine 
and should be rejected without further investigation. 

The opalescent green tinge on engine oils is due to their 
adulteration with either kerosene or some lighter hydrocarbon 
which is not a lubricant and which is easily volatilized. All 
lubricating oils should be entirely free from grit, the presence of 
which may be discovered by the use of a magnifying glass. 

349. Volatile Oils. Coal oil, otherwise known as kerosene, 
refined petroleum oil, and mineral sperm oil are among the most 
fluid oils and are excellent for cleaning bearings. The vapors 
from such volatile oils as benzine, naphtha and turpentine, when 
mixed with air, form a dangerous explosive. Considerable care, 
therefore, should be exercised in their use, which in the machine 
shop is generally for cleaning purposes. 



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FRICTION, LUBRICANTS AND LUBRICATION 



67 



Oil Specifications 

351. Table of Chemical and Physical Properties of 12 Ordi- 
nary Lubricating Oils. 



Kind of OU 


Use and Adaptation 


Gravity 


Cold 
Test 


Flash 
Teat 


Fire 
Test 


Viscosity 
atyo' 


High Pressure Cyl- 
inder Oil 


For steam cylinders 
using diy steam at 
pressures from 110 
to 210 lbs. 


25^ 

to 

24.5^ 


30° 


600° 

to 

610° 


645° 

to 

660° 

600° 

to 

630° 


175 

to 
205 


General Cylinder Oil 


For steam cylinders 
using dry steam at 
75 to 100 lbs. 

For air compressor 
cylinders when 
made from steam 
refined mineral 
stock and when vis- 
cosity is 200. 


26^ 

to 

25.5** 


30° 


550° 

to 

685° 


180 

to 

190 


Wet Cylinder Oil... 
Remark 1 


For use where the 
steam is moist, 
especially in com- 
pound and triple- 
expansion engines. 


25.8° 

to 
25.3** 

26.5° 


30° 


560° 

to 

685° 


600° 

to 

630° 


150 
to 
185 


Gas Engine Cylinder 
Oil 


For gas engine cyl- 
inders. 

Neutral mineral oil 
compounded with 
an insoluble soap 
to give body. 


30° 


320° 


360° 


300 


Remark 2 




Automobile Gas En- 
gine Oil 
Remark 3 


For automobile gas 
engines and similar 
woik. 


29.5° 


30° 


430° 


485° 


195 


Heavy Engine and 
Machinery Oils. .. 


For heavy slides and 
bearings, shafting 
and horizontal sur- 
faces. 


30.5° 

to 
29.5° 


30° 


400° 


440° 
to 
460° 


170 
to 
195 


General Engine and 
Machine Oils 


For hi^-speed dyna- 
mos and maciiines. 


30.8° 
to 
30° 


30° 


400° 

to 

420° 


450° 

to 

470° 


175 
to 
190 



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58 ENGINEERING AND SHOP PRACTICE 

351. Table of Chemical Properties (continued). 



Kind of OU 


Use and Adaptation 


Gravity 


Cold 
Test 


Flash 
Test 


Fire 
Test 


Viscosity 
at 70' 


Fine and Light Ma- 
chine Oils 


For fine work from 
printing presses to 
sewing machines 
and typewriter oils. 
With a cold test of 
25° to 28° and a 
viscosity of 140° 
this makes an ex- 
cellent spindle oil. 


32.5° 

to 
30.2° 


30° 


400° 


440° 


110 

to 

160 


Cutting and Dissi- 
pating Oils 

Remark 4 


For cutting tools, 
screw cutting and 
similar work. 


27° 
to 
23° 


30° 


410° 

to 

420° 


475° 

to 

480° 


175 
to 
210 


Refrigerating Oils . . 


For ice machinery. 


30.2° 


0° 


200° 


225° 


165 


Wet Service and Ma- 
rine Oils 

Remark 5 


For marine service or 
where a great deal 
of moisture must 
be handled. 

They arc used in 
special work and 
for heavy press- 
ures moving at 
slow velocities. 


28° 


30° 


430° 


475° 


230 


Greases 















Remark 1. May contain not over 2% to 6% of refined acidless tallow 
oil in the high-pressure oils, and not over 6% to 12% in the low-pressure 
oils. 

Remark ^. The reason for using an insoluble soap such as oleate of 
aluminum is that it is impossible to decompose the soap with a high heat — 
the soap, although not a lubricant, is a vehicle for carrying some oil. 

Remark 3. Owing to a lack of body this oil will not interfere with the 
sparking l)y depositing carbon on the platinum point. 

Remark 4. Sometimes contains as much as 40% of lard oil. A pure 
strained lard oil, though more expensive, is probably superior to any mix- 
ture for this purpose. 

Remark 5. May contain 30% to 40% of pure strained lard oil. 

Fig. 351. 



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FRICTION, LUBRICANTS AND LUBRICATION 



59 



352. Lubricant Friction. In a table of the comparative fric- 
tion of different lubricants under the same circumstances, tem- 
perature 90^, oil bath, Tower gives the following: 



Spem Oil 100% 

Rape Oil 106% 

Mineral Oil 129% 



Laid Oil 135% 

Olive Oil 135% 

Mineral Grease 217% 



353. Lubricant Application. The following table, Fig. 353, 
prepared from various sources, is intended to give some idea of 
the comparative values of the various methods of lubrication; a 
value of 1 being given to a method whose coefficient of friction 
is .01. 



Method of Lubrication 



Oa Bath 

Pad under Bearing 

Siphon Lubricator 

Oil Cups, Restricted Hates of Feed 
Intermittent Application 



Coefficient of Friction 


Comparative Value 


.00139 


7.19 


.009 


1.11 


.0098 


1.02 


.01 to .012 


1 to .83 


.01 to — 


1 to — 



Fig. 353. 

Solid Lubricants 

361. Use of Solid Lubricants. In many instances the use of 
some form of solid lubricant will be found advantageous, especially 
where heavy pressures are used and for such troubles as binding, 
heating and grunting, where oil by its very nature would fly 
from or be forced out of the bearings. 

362. Graphite. Pure, flaked graphite is the best solid lubri- 
cant known; it is generally mixed in some oil which provides a 
means of getting it to the rubbing parts. Its manufacturers 
make the following claims regarding it: (1 ) It effects a saving of 
20% to 90% in oil or grease; (2) it increases the eflJciency of 
other lubricants of the best quality many hundred per cent.; (3 ) it 
is incomparable in breaking in new engines and machines, and 
(4) it is the only perfect lubricant for gas-engine cylinders. 

This statement should be questioned as many users of small 
engines report trouble with deposits of graphite on the spark 
terminals. To obtain these results the graphite should be en- 
tirely free from any grit or foreign matter and should be water- 



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60 ENGINEERING AND SHOP PRACTICE 

dressed and air-floated. Furthermore graphite is entirely inert 
and not affected by heat, cold, steam, acid or any known chemical; 
it largely increases the lubricating values of any oil or grease 
and may be mixed in water, oil or grease, or used dry according 
to the requirements of the conditions. 

363, Talc. Talc, sometimes called soap stone, in the form of 
powder and mixed with a heavy oil, grease or soap, is occa- 
sionally used on surfaces of wood, working against either wood 
or iron. 

Heat Dissipating Lubricants 

371. Twofold Action of Heat-dissipating Lubricants. The 

action of cutting or heat-dissipating lubricants is generally two- 
fold; not only do they reduce the friction between the chip and 
the tool, but when used in sufficient quantities they successfully 
dissipate the heat generated, thus increasing the output and the 
life of the cutting edge in some instances as much as 40%. 

372. Heat-dissipating Mixtures. Lard or sperm oil is the 
best lubricant for cutting wrought iron and steel, though many 
of the cutting oils on the market give efficient service. 

Soda water, a mixture of one part sal soda (sodium carbonate ) 
with twenty parts of water, forms an excellent lubricant for this 
same purpose, and one that will not rust. 

Soft-soap mixed with enough water to make it flow freely is 
sometimes used, while water alone gives the peculiarly bright 
surface which is known as a " water cut." 

373. Dry Cuts. Cast iron, copper and brass are generally 
cut dry. Babbitt metal is usually cut dry, though a copious 
supply of kerosene will produce excellent results. 



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CHAPTER IV 

CUTTING TOOLS 

Discussion 

411. Governing Conditions. In general, all metal-cutting 
tools are modifications of the wedge, both in design and opera- 
tion. They should always be as sharp as the conditions will 
allow. In discussing the metal-working tools used in machines 
there are four governing conditions to be considered: (1) The 
keenness of the tool; (2) the strength and durability of the 
cutting edge; (3) the relative position of the tool and the work, 
and (4) the shape of the tool and the material to be cut. 

412. The Keenness of the Tool. Since the action of the tool 
is that of a wedge, the more acute the angle of keenness — fc in 
the figures — ignoring all other conditions, the less the resistance 
offered to the removal of the chip. 

413. The Strength and Durability of the Cutting Edge. The 
strength and durability of the cutting edge is as important a 
factor as that of keenness. Upon it depends the amount of 
stock that can be removed at a cut, the feed and the interval 
between grindings. To obtain greater durability and strength, 
we give additional support to the cutting edge by decreasing 
both the clearance, c, and the top rake, ir; these angles depending 
upon the material to be cut and the position of the tool. 

414. The Relative Position of the Tool and Work. It is 
evident that when the cutting edge is tangent to the work, the 
least possible resistance is offered in removing the chip and that 
this is its ideal position (Fig. 414a). Owing to the fact that the 
point of tangency changes with every chip, it is necessary to set 
the tool somewhat lower than this position. Considering the 
tool alone, without any reference to its relation to the work, we 
will draw AB parallel to the base of the tool and D perpendicular 
to AB, both through the cutting edge of the tool (Fig 4146). 
The angle tr is called top rake; the angle c clearance; while keen- 

61 



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62 



ENGINEERING AND SHOP PRACTICE 



ness refers to the angle k. By an inspection of Fig. 414o it will 
be found that the angles of clearance and top rake change with 
every position of the tool. 




c ID 
Fig. 414a, 6, c. 

415. The Shape of the Tool and the Material to be Cut. The 

material to be cut determines the shape of the tool and its effective 
angles of clearance, keenness and top rake. The conditions 
governing these angles, in turn, depend upon (a) the kind of 
metal to be cut; (b) the hardness of the metal; (c) the character 
of the cut, roughing or finishing — and (d) the manner of pre- 
senting the tool to the work. As a general statement, the angle 
of keenness is more acute for the soft metals, such as wrought 
iron and mild steel — except where the metals have a tendency 
to draw in the tool — than for the harder ones such as chilled 
cast iron and tool steel. Copper and its various alloys such as 
brass, bronze, etc., have a tendency to draw in the tool, and for 
working these alloys the angles of the tool are made very blunt; 
in fact, negative rake is often given. 

In the deep coarse-fed roughing cuts, the cutting edge is at e, 
(Fig. 4146), and the keenness is obtained from the side rake, 
sr; while, in the light, finer fed finishing cuts, characteristic in 
small work, the cutting edge is at 0, and keenness is obtained 
from the top rake. This statement also has reference to the 
manner of presenting the tool to the work. 

Feeds and Speeds 

421. The Surfaces of Metals and the Character of the Chip. 

The surface of most metals, and especially that of castings, is 
usually much harder than the interior. In wrought metals, such 
as machinery steel, etc., this hardness, ofttimes negligible, is due 
to the direct action of the rolls on the surface; in castings this 
hardness is due to the chilling action of the surface of the mold. 
For this reason the first roughing cut should go entirely below 



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CUTTING TOOLS 63 

or beneath this hard surface film; otherwise the tool heats and is 
rapidly dulled. 

The proper adjustment of the tool is had when it produces a 
clean, smooth, rather tightly curled chip, as contrasted with one 
that is rough and crumbling. According to condition 3 this 
brings the cutting edge of a properly ground tool slightly above 
the line of centers. 

422. General Rules Relative to Feeds and Speeds. Practice 
has shown that metal can be removed more rapidly by taking 
heavy cuts at relatively low speeds; the greater the reduction in 
diameter the finer the feed. In general, this rule applies to 
roughing cuts; to produce smooth, finished surfaces, however, a 
light cut at a fast speed and fine feed is used. The feed and 
speed used in any case are governed by the following limitations: 
(1 ) The strength of the tool with reference to breakage — to 
avoid breakage see that the tool is properly adjusted and never 
start the machine backward. (2) The wearing of the cutting 
edge. To avoid excessive wear sharpen and set the tool so as 
to cleave the chip off rather than to pulverize it. (3 ) The heating 
and consequent loss of temper of the cutting edge. To obviate 
this difficulty the tool should be kept sharp; the trying to push 
off the stock with a dull edge consumes more time and tool than 
the grinding necessary to keep it sharp. (4) A weak machine 
drive. See that the driving belt is tight — not loose enough to 
slip — and on the proper pulley. (5 ) Lack of stability in the 
work. A weak piece of work, so weak as to spring, must be 
either humored or supported. 

The difficulty of recommending a definite feed and speed per 
minute in any case will be seen upon referring to the discussion 
in the abstracts of the papers on this subject which appear in 
Sections 424, 425, 426 and 427. 

Precautions. The cutting edge of the tool should be as near 
to the tool post as is possible without interference between the 
dog and the carriage. 

In order to reduce the friction on the dead center, always 
feed toward the live center. 

Never reverse the feed or throw in the back gears while the 
machine is running. 

423. Remarks Concerning the Author's Investigations. In the 
more recent experiments, especially in those pertaining to high- 



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64 ENGINEERING AND SHOP PRACTICE 

speed tool steels, a great number of valuable data have been 
compiled and practice long considered excellent becomes obsolete 
in the light of these investigations. The following matter 
abstracted from an article on "Feeds and Speeds/' published 
by the author in the American Machinist, Dec. 25, 1902, though 
in minor respects superseded by more recent data, is given, 
however, as being the best available for a general presentation of 
the subject to the student. The article, written before the general 
use of high-speed tool steels, deals necessarily with ordinary 
tool steels, i.e. those varying from 70- to 90-point carbon and 
tempered in the ordinary manner. 

For data relative to the size of chip, speed, feed and the 
horse-power required to remove it, the student is referred to 
Chapter 20, "Motor Drives," etc.. Section 2054. 

424. Author's Research. — Ordinary Low-speed Tool Steels. 
From the pages of such technical and trade periodicals as the 
American Machinist , Machinery , etc., and from those of the 
excellent catalogs which it is the habit of our machine builders 
to produce, data relative, generally, to the maximum feeds and 
speeds were separated and tabulated. This was done with special 
reference to the determining of the best feed and speed to be 
used in the removal of a maximum amount of stock, screw- 
machine practice being used as one of the guide posts in our 
journey of discovery. 

To discover and ascertain the nature of any existing law was 
the next step. The data relative to each machining process for 
a given material were transferred to squared paper, where the 
curve was plotted; the ordinates representing speeds, the abscissas 
the feeds. Brass, being the softest material, was first plotted; its 
values for turning operations were plotted for the four following 
reductions: (1) ^ reduction in the diameter, ordinary practice 
and small reductions being here included; (2) J reduction of 
diameter; (3) } reduction of diameter; (4) i reduction in diam- 
eter. The average feed used for small reductions and rapid 
cutting was found to be about 20 per inch; while that for i and 
similar large reductions was about 100 per inch. The feeds used 
for } and J reductions were found to be grouped near what would 
be the second and third terms of a geometrical progression between 
these two values. 

In plotting our final diagram, the feeds corresponding to 



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CUTTING TOOLS 



65 



reductions of ^, J, J and J were made 20, 34.2, 58.48 and 100 
respectively; i.e. they were arranged in geometrical progression. 
To these special ordinates were transferred the data for such 
milling, drilling and planing operations as were made with what 
might be termed correspondingly heavy cuts; the word reduction, 
in reference to any other operation save that of turning, being 
of course a misnomer. After plotting the curves for brass, the 
task of plotting the curves for cast iron, wrought iron, machinery 
steel and tool steel proved comparatively easy. 

A careful examination of these several plottings seems to 
reveal the important fact that, not only did the lines for the 
several operations on the same material radiate from an appar- 
ently common origin, but that the lines for these operations for 
all the materials did likewise; that is, they justified one in 
assuming that they had a common origin. This being the case, 
a single plotting was made, the lines being transferred from the 
four sheets, and the values plotted from a common origin. The 
equations for these curves formed a step deemed necessary for 
the compilation of an accurate table of maximum feeds and speeds 
for these materials. These equations were corrected and simplified 
without materially altering their values. 

Corrected Equations 



Bras 



Cast Iron 



Wrought Iron and 
Mach. Sted 



ToolSted 



Turning . 
Milling . . 
Drilling . 
Planing . 



S«-f F + 106 
S-.-iF+ 80 
S = -JF+ 64 
S«-1F+ 53 



S«-7»jFf66 
S«-3'^F + 50 
S--i F+39 



S«-§ F + 53 
S = -iF+40 
S--iF+32 
S--JF+27 



S /,F + 33 

S--/jF+25 
S=.-i F+20 
S AF+17 



A careful examination of these corrected equations, with due 
consideration as to the manner in which they were obtained, will 
justify us in stating that another important fact is revealed, 
namely, that the various operations possess values and relations 
irrespective of the materials on which they were performed. To 
be more specific, assigning a value of unity to turning operations, 
we may say that the value for milling operations is J, drilling J, 
and planing i. Here are data that corroborate what we already 
know, namely, that the lathe is more efficient than any of our 



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66 ENGINEERING AND SHOP PRACTICE 

other machine tools; how much, is of course desirable informa- 
tion. We might say, too, that it behooves the intelligent designer 
or foreman to plan the greater part of his work for the lathe, 
leaving a minor part to be accomplished by the planer. 

One more important fact, which may be deduced from the 
equations, is the relation which we find to exist between what 
we might call the working texture of the average materials used 
in our shops. He who has to do with the problems of cost 
reduction will welcome this and kindred data in reference to his 
stock materials. It was discovered that when the value of 16 
was assigned to brass, cast iron had a value of 10, wrought iron 
and machinery steel 8 and tool steel a value of 5. 

Turning our attention now to the diagrams, of which we have 
three, one containing the data for brass and tool steel (Fig. 424a) 
one for cast iron (Fig. 4246) and one for wrought iron and 
machinery steel (Fig. 424c), we find them to be, to a large ex- 
tent, self-explanatory; however, a few words of explanation may 
prove of some assistance. The lines marked '* Turning," "Mill- 
ing," "Drilling" and "Planing" respectively give the best speed 
and feed values for a predetermined reduction. By the term 
"best" speed and feed values the author wishes to convey the 
idea that this is the speed and feed that will remove a maximum 
amount of material when due consideration is given to economy 
and the time required for changing and grinding the tools. 
These values, it must be remembered, are for materials of aver- 
age texture and composition, special materials requiring, of 
course, special feeds and speeds. Assuming that we have a piece 
of cast iron 2" in diameter which we wish to turn down to 
li'^ in diameter, that is, a \ reduction; having determined upon 
the reduction, J, we follow the line marked " turning" in the chart 
for cast iron to its intersection with our \ reduction lines; dropping 
vertically on this line, we read our feed, 34.2. Passing horizon- 
tally from the intersection to the right, we read the speed 52. 
Having now determined the speed in feet per minute, it is only 
necessary to determine the number of revolutions that will give 
to the piece this speed. Consulting the "Table of Revolutions 
for Given Diameters and Cutting Speeds" (Section 428), (Fig. 
428), we find that our piece must make about 95 revolutions 
per minute. The table of "Cutting Speeds for Common Reduc- 
tions" (Fig, 424d) gives the formulas and tabulated speeds as 



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CUTTING TOOLS 



67 



obtained from the charts, it being assumed that this is a more 
convenient form when seeking ordinary reductions. 



Q 



I 

9 



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3 ^ 



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ENGINEERING AND SHOP PRACTICE 



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70 



ENGINEERING AND SHOP PRACTICE 



Table op Cutting Speeds for Common Reductions. Low-speed Steels 



Speeds in Feet Per Minute 


Operation 


Formula 


F-20 


F-34.a 


F- 58-48 


F-100 








^s reduction and 


1 reduc- 


i reduc- 


i reduc- 








average practice 


tion 


tion 


tion 








on light cute 








Brass 


Turning 


s = 


-i F + 106 


93 


83 


67 


39 


Milling 


s = 


- J F+ 80 


69 


62 


50 


30 


Drilling .... 


s= 


-* F-f 64 


56 


50 


40 


24 


Planing 


s = 


- J F+ 53 


46 


42 


34 


20 


Cast Iron 


Turning 


s = 


-T*iF+ 66 


58 


52 


42 


25 


Milling 


s = 


-A F+ 50 


43 


39 


31 


18 


Drilling 


s = 


- i F+ 39 


35 


31 


25 


15 


Planing 


s = 


-/rF+ 33 


29 


26 


21 


12 






Wrought Iron and Machir 


lery Steel 






Turning 


s = 


- i F+ 53 


46 


42 


34 


20 


Milling 


s = 


-J F+ 40 


35 


31 


25 


15 


Drilling 


s = 


-i F+ 32 


28 


25 


20 


12 


Planing 


s = 


-i F+ 27 


23 


21 


17 


10 








7^00/ Steel 


26 






Turning 


s = 


-jVF+ 33 


29 


21 


12 


Milling 


8 = 


-A F-f 25 


22 


20 


16 


9 


Drilling .... 


s = 


-i F+ 20 


17 


16 


13 


7 


Planing 


s = 


-^F4- 17 


14 


13 


10 


6 



Fig. 424rf. 

425. Abstract of Professor Nicholson's Investigations. Dr. 

J. T. Nicholson, in a valuable paper read before the American 
Society Mechanical Engineers, June, 1904, recording exhaustive 
experiments with a lathe tool dynamometer, arrives at the follow- 
ing conclusions: In outlining the series of tests, he says: *'For 



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CUTTING TOOLS 71 

both cast iron and steel it was the intention to make trials with 
each of four different traverses (feeds), ^''y J'', J'' and f' with 
four depths of cut for each traverse, i", {", %" and J''. This 
scheme was carried out in the case of cast iron so far as was 
possible with the means available, for each of the four cutting 
angles of 45, 60, 75 and 90°/' 

Speaking in reference to his Table 2 recording the stresses 
obtained, in accordance with the above schedule, on cast iron 
with a speed of 25 feet per minute, he says: 

(1 ) This plate indicates a somewhat lower stress (tons per 
square inch) for wide than for fine traverses (feeds), although 
this conclusion does not appear to hold in its entirety, especially 
for the keenest cutting angle used, 45°. 

(2) For a given traverse the cutting force is simply pro- 
portional to the depth of the cut [for a contrary finding see Sec- 
tions 426 and 427] or that the cutting stress is constant for a 
given width of traverse and a given tool angle. 

(3) The variation of the cutting stress with the cutting 
angle is very marked. It varies by nearly 100% of its smallest 
value, which takes place in every case for a cutting angle of about 
60°. However, this angle of minimum cutting force is by no 
means that of greatest durability. A cutting angle of 80° is 
that indicated as being best for shop use, and the cutting stress 
for this angle is about 75 tons per square inch. 

Note, In a duration test of the different cutting angles on 
cast iron, with a cutting speed of 44 feet per minute, a cut VV' 
in depth and a traverse of ^"^ Professor Nicholson found that his 
experiments verified the "Manchester Report,'' which recommends 
a true cutting angle of 81°. He says (4 ) ''Tools should therefore 
be ground for a maximum endurance in the cutting of cast iron 
in ordinary shop practices, so that their true cutting angles are 
about 81°, or if they are allowed 6° clearance for working on the 
level of lathe centers, they should have an included angle (angle 
of keenness ) of 75°. 

(5) The variation of the cutting stress with the traverse — 
speed 50 feet per minute — in the case of soft steel is somewhat 
complicated. For keen cutting angles (below 75°), fine traverses 
require less cutting force than wide ones; while for blunt-nosed 
tools (i.e. cutting angles greater than 75°) the reverse is the 
case, and the fine traverse cut requires the greater effort to 



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72 ENGINEERING AND SHOP PRACTICE 

remove. At a cutting angle of 75° the stress is the same whether 
the traverse be ^^ or i" and has the value of about 100 tons 
per square inch. It is curious to remark that this angle of 75° 
is also about the best angle for shop use as shown by the du- 
rability trials. 

(6 ) With medium fluid pressed steel two series of endurance 
tests were made, one at 74 feet per minute and one at 73 feet 
per minute cutting speed; the cut in both cases being J'' deep 
and i" wide. Taken altogether these tests seem to show that a 
cutting angle of about 70° (angle of keenness 65° ) is that which 
will last the longest in rapid cutting; the plan angle of the cutting 
edge was 45° throughout. 

426. Abstract of President Taylor's Investigations. (High- 
speed Steels.) The discoveries of Pres. F. W. Taylor and his 
associates are of such a character and magnitude as to render 
impossible any but an inadequate r6sum6. These investigations 
were presented before the American Society of Mechanical Engi- 
neers in December, 1906, and form a part of volume 28 of the 
Proceedings of that Society. 

The paper deals with the problem under the following heads: 

(1 ) Action of the Tool and Its Wear in Cutting Metals, 

(2 ) How Modern High-speed Tools Wear. 

(3 ) How to Make and Record Experiments, 

(4) Lip and Clearance Angles of Tools, The important 
conclusions under this heading are: 

(a) For standard shop tools to be ground by a trained 
grinder or on an automatic grinding machine, a clearance angle 
of 6° should be used for all classes of roughing work. 

(6) In shops in which each machinist grinds his own tools a 
clearance angle of from 9° to 12° should be used. 

For standard tools to be used in a machine shop for cutting 
metals of average quality: Tools for cutting cast iron and the 
harder steels beginning with a low limit of hardness, of about 
carbon 0.45%, say, with 100,000 pounds tensile strength and 
18% stretch, should be ground with a clearance angle of 6°, 
back slope 8° and side slope 14°, giving a lip angle of 68°. 

For cutting steels softer, say, than carbon 0.45%, having 
about 100,000 pounds tensile strength and 18% stretch, tools 
should be ground with a clearance angle of 6°, back slope of 8°, 
side slope of 22°, giving a lip angle of 61°. 



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CUTTING TOOLS 73 

For shops in which chilled iron is cut a lip angle of from 
86° to 90° should be used. 

In shops where work is mainly upon steel as hard or harder 
than tire steel, tools should be ground with a clearance angle of 
6°, back slope 5°, side slope 9°, giving a lip angle of 74°. 

In shops working mainly upon extremely soft steels, say 
carbon 0.10% to 0.15%, it is probably economical to use tools 
with lip angles keener than 61°. 

The most important consideration in choosing the lip angle 
is to make it sufficiently blunt to avoid the danger of crumbling 
or spalling at the cutting edge. 

Tools ground with a lip angle of about 54 degrees cut softer 
qualities of steel, and also cast iron, with the least pressure of 
the chip upon the tool. The pressure upon the tool, however, 
is not the most important consideration in selecting the lip angle. 

In choosing between side slope and back slope in order to 
grind a sufficiently acute lip angle, the following considerations, 
given in the order of their importance, call for a steep side slope 
and are opposed to a steep back slope: 

(a) With side slope the tool can be ground many more times 
without weakening it. 

(b) The chip runs off sideways and does not strike the tool- 
posts or clamps. 

(c) The pressure of the chip tends to deflect the tool to one 
side and a steep side slope tends to correct this by bringing the 
resultant line of pressure within the base of the tool. 

(d) p]asier to feed. 

The following consideration calls for at least a certain amount 
of back slope. An absence of back slope tends to push the tool 
and the work apart, and therefore to cause a slightly irregular 
finish and a slight variation in the size of the work. 

(5 ) Forging and Grinding Tools. The important conclusions 
under this heading are: 

The shapes into which tools are dressed and the ordinary 
methods of dressing them are highly uneconomical, mainly 
because they can be ground only a few times before requiring 
redressing. 

The tool steel from which the tool is to be forged should be 
one and one half times as deep as it is wide. 

To avoid the tendency of the tool to upset in the tool post 



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74 ENGINEERING AND SHOP PRACTICE 

under pressure of the cut, the cutting edge and the nose of the 
tool should be set well over to one side of the tool. 

Tool builders should design lathes, boring mills, etc., with 
their tool posts set down lower than is customary below the 
center of the work. 

In choosing the shape for dressing a tool, that shape should 
be given the preference in which the largest amount of work can 
be done for the smallest combined cost of forging and grinding. 

Forging is much more expensive than grinding, therefore the 
tool should be designed so that it can be ground, 

(a) the greatest number of times with a single dressing; and 

(6) with the smallest cost each time it is ground. 

The best method of dressing a tool is to turn its end up high 
above the body of the tool. Tools can be entirely dressed by 
this means in two heats. 

The importance of carefully heating the tool for dressing. 

Fire or heat cracks in tools are due to the following causes: 

(a ) Seams or internal cracks in bar of tool steel. 

(b ) Nicking or breaking the bar of tool steel while it is cold. 

(c) Failing to turn the tool over and over while heating it 
for forging. 

(d) Too rapid heating, particularly at the start, in a hot fire. 
It is of great importance to properly adjust the amount of 

work to be done in the smith shop and on the grinding machine, 
in making the tool. 

(a) Too much work is generally done in dressing tools to 
exact shape in the smith shop, particularly when automatic 
grinding machines are used. 

(6) A limit gage should be used by the smith to properly 
regulate the proportion of smith work and grinding work in 
making the tool. 

More tools are ruined in every machine shop through overheating 
in grinding than from any other cause. 

The most important consideration is how to grind tools rapidly 
without overheating them. 

To avoid overheating, a stream of water amounting to five 
gallons per minute should be thrown, preferably at a slow velocity, 
directly on the nose of the tool where it is in contact with the 
emery wheel. 

To avoid overheating where tools are ground by hand or with 



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CUTTING TOOLS 75 

an automatic tool grinder, the surface of the tool should never 
be allowed to fit closely against the surface of the grindstone. 
To prevent this, tools should be constantly moved or wobbled 
about during the operation of grinding. 

To lessen the danger of overheating on the emery wheel and 
to promote rapid grinding, tools should be dressed so as to leave 
the smith shop with a clearance angle of about 20°, while 6° only 
is needed for cutting. 

Flat surfaces upon tools tend far more than curved surfaces 
to heat tools in grinding. 

Tools with keen lip angles (i.e. steep side slopes) are much 
more expensive to grind than blunt lip angles. 

It is economical to use an automatic tool-grinding machine 
even in a small shop. 

There is little economy in ^n automatic grinder for any shop 
unless standard shapes have been adopted for tools, and a large 
supply of tools is kept always on hand in a first-class tool-room 
so that tools of exactly the same shape can be ground in large 
batches or lots. 

Corundum wheels made of a mixture of grit size No. 24 and 
size No. 30 are the most satisfactory for grinding ordinary shop 
tools. 

In grinding flat surfaces skilful hand grinders invariably keep 
the tool wobbling about on the face of the grindstone in order to 
avoid heating. 

(6) Pressure of the Chip upon the Tool. The most important 
conclusions arrived at on this subject are, for cast iron: 

Total pressure of chip on tool in cutting cast iron, of the 
different qualities experimented upon by us, varies between the 
low limit of 35 tons (2000 pounds) per square inch, sectional area 
of chip, for soft cast iron when a coarse feed is used, and 99 tons 
per square inch, sectional area of chip, for hard cast iron, when 
a fine feed is used. 

In cutting the same piece of cast iron, the pressure of chip 
on the tool per square inch sectional area of chip grows con- 
siderably greater as the chip becomes thinner and slightly greater 
as the cut becomes more shallow in depth. The following are 
the high and low limits of pressure per square inch of sectional 
area of the chip when light and heavy cuts are taken on the 
same piece of cast iron: 



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76 ENGINEERING AND SHOP PRACTICE 

Depth of Cut J^ X Feed 0.0328*: Total Pressure per Sq. In. Sec- 
tional Area of Chip, 128,000 
pounds; 

Depth of Cut ii" X Feed 0.1292*: Total Pressure per Sq. In. Sec- 
tional Area of Chip, 75,000 
pounds. 

The same fact mathematically expressed is that in cutting the 
same piece of cast iron the pressure of the chip on the tool per 
square inch sectional area of chip grows greater as the thickness 
of the chip grows less in proportion to (thickness of the feed) * 
orF*. 

The following formula expresses the general relation existing 
between the depth of cut and the feed, and the pressure on the 
tool for all the grades of cast iron experimented upon: 

m which 

P = The pressure on the tool; 

D = Depth of Cut in Inches; 

F = Feed in Inches. 

C = A constant depending upon the softness or the hardness 
of the cast iron, and which varies between the limits of 45,000 
for soft and 69,000 for hard cast iron. 

The pressure of chip per square inch of section also grows 
greater as the depth of the cut grows less in proportion to (depth 
cut) ^ or D^. 

The effect upon the pressure of the chip on the tool of a change 
in the thickness of the feed and the depth of the cut is the same 
for hard and soft cast iron, and is represented by the same gen- 
eral formula with a change merely of the constant. 

In taking cuts having the same depth and the same feed, the 
pressure of the chip on the tool becomes slightly greater the 
larger the cutting tool that is used. This increase in the pressure 
follows from the fact that the larger the curve of the cutting edge 
of the tool, the thinner the shaving becomes. 

The most important conclusions arrived at regarding the 
pressure of the chip on the tool in cutting steel are: 

The total pressure of the chip on the tool in cutting steel of 
the different qualities experimented upon by us varies between 
the low limit of 92 tons (2000 pounds) per square inch of sectional 



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CUTTING TOOLS 77 

area of the chip, and the high limit of 168 tons (2000 pounds) 
per square inch sectional area of the chip. 

In cutting the same piece of steel, the pressure of the chip on 
the tool per square inch of sectional area of the chip grows very 
slightly greater as the chip becomes thinner, and is practically 
the same whether the cut is deep or shallow. The following 
formula illustrates the relative pressure of a thin feed on the 
one hand and a coarse feed on the other. 

Depth of Cut ^^ X Feed 0.0156'': Total Pressure per Sq. In. Sec- 
tional Area of Chip, 295,000. 

Depth of Cut iY X Feed 0.125'': Total Pressure per Sq. In. Sec- 
tional Area of Chip, 257,000. 

The same fact mathematically expressed is that in cutting 
the same piece of steel, the pressure of the chip on the tool per 
square inch of sectional area of the chip, grows greater as the 
thickness of the chip grows less in proportion to (thickness of 
the feed) * or F*. The pressure of the chip is in direct pro- 
portion to the depth of the cut. 

Within the limits of cutting speed in common use, the pres- 
sure of the chip upon the tool is the same whether fast- or slow- 
cutting speeds are used. 

The pressure of the chip upon the tool depends but little upon 
the hardness or softness of the steel being cut, but increases as 
the quality of the steel grows finer. In other words, high grades 
of steel, whether soft or hard, give greater pressures on the tool 
than are given by inferior qualities of steel. 

The pressure of the chip on the tool per square inch of sectional 
area of the chip depends upon both the tensile strength of the 
steel and its percentage of stretch, and increases both as the 
tensile strength and stretch increase; although a higher tensile 
strength has more effect than a large percentage of stretch in 
increasing the pressure. 

Lastly, by far the most important conclusion arrived at 
by us in the field of " Pressure of the Chip on the Tool " is that 
the gearing designed in lathes, boring mills, etc., for feeding the 
tool should be sufficiently strong to deliver at the nose of the 
tool a feeding pressure equal to the entire driving pressure of the 
chip upon the lip surface of the tool. This fact was developed by 
us in an experiment made in the year 1883 in the works of the 



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78 ENGINEERING AND SHOP PRACTICE 

Midvale Steel Company, and had such an important bearing on 
the cost of turning out the product in the machine shop of those 
works that the results of this one simple investigation more than 
paid for all the experiments in the entire field of cutting metals 
undertaken in the Midvale Steel Works. 

(7) Cooling the Tool with a Heavy Stream of Water. Chief 
among the conclusions derived along these lines are: 

With high-speed tools a gain of 40% can be made in cutting 
steel or wrought iron by throwing, in the most advantageous 
manner, a heavy stream of watet upon the tool. 

In designing slide rules or tables, etc., for assigning daily 
tasks to machinists, a 33% increase in cutting steel or wrought 
iron should be allowed for instead of 40%, owing to the fact 
that workmen are more or less careless in directing the stream 
of water to the proper spot upon the tool. 

A heavy stream of water (3 gallons per minute) for a 2^^ x 2i^ 
tool, and a smaller quantity as the tool grows smaller, should be 
thrown directly upon the chip at the point where it is being 
removed from the forging by the tool. Water thrown upon any 
other part of the tool or the forging is much less efficient. 

The gain in cutting speed through the use of water on the 
tool is practically the same for all qualities of steel from the 
softest to the hardest. 

The percentage of gain in cutting speed through the use of 
water on the tool is practically the same whether thin or thick 
chips are being removed by the tool. 

With modem high-speed tools a gain of 16% can be made by 
throwing a heavy stream of water on the chip in cutting cast iron. 

To get the proper economy from the use of water in cooling 
the tool, the machine shop should be especially designed and the 
machine tools especially set with a view to the proper and con- 
venient use of water. 

In cutting steel, the better the quality of tool steel the greater 
the percentage of gain through the use of a heavy stream of 
water thrown directly upon the chip at the point where it is 
being removed from the forging by the tool. The gain for the 
different types of tools in cutting steel is: 

(a) Modem high-speed tools 40%. 

(6) Old-style self-hardening tools 33%. 

(c) Carbon tempered tools 25%. 



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CUTTING TOOLS 79 

This fact stated in diflFerent form is that: The hotter the nose 
of the tool becomes through the friction of the chip, the greater 
is the percentage of gain through the use of water on the tool. 

(8) Chatter of Tools. The following are the general conclu- 
sions arrived at under this heading: 

Chatter is the most obscure and delicate of all problems 
facing the machinist, and in the case of castings and forgings of 
miscellaneous shapes, probably no rules or formulae can be devised 
which will accurately guide the machinist in taking the maximum 
cuts and speeds possible without producing chatter. 

It is economical to use a steady rest in turning any piece of 
cylindrical work whose length is more than twelve times its 
diameter. 

Too small lathe-dogs or clamps or an imperfect bearing at 
the points at which the clamps are driven by face plates produce 
vibration. 

To avoid chatter, tools should have cutting edges with curved 
outlines and the radius of curvature of the cutting edge should 
be small in proportion as the work to be operated on is small. 
The reason for this is that the tendency of chatter is much greater 
when the chip is uniform in thickness throughout, and that tools 
with curved cutting edges produce chips which vary in thickness, 
while those with straight cutting edges produce chips uniform in 
thickness. 

Chatter can be avoided, even in tools with straight cutting 
edges, by using two or more tools at the same time in the same 
machine. 

The bottom of the tool should have a true, solid bearing on 
the tool support, which should extend forward almost directly 
beneath the cutting edge. 

The body of the tool should be greater in depth than its 
width. 

Chatter caused by modifications in the machine may be 
classified as follows: 

(a) It is sometimes caused by badly made or fitted gears. 

(fc) Shafts may be too small in diameter or too great in length. 

(c) Loose fits in the bearings and slides may occasion chatter. 

(d) In order to absorb vibrations caused by high speeds, 
machine parts should be massive far beyond the metal required 
for strength.. 



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80 ENGINEERING AND SHOP PRACTICE 

Chatter of the tool necessitates cutting speeds from 10% to 
15% slower than those taken without chatter, whether tools are 
run with or without water. 

Higher cutting speed can be used with an intermittent cut 
than with a steady cut. 

Of all the difficulties met with by a machinist in cutting 
metals, the causes for the chatter of the tool are perhaps the 
most obscure and difficult to ascertain, and in many cases the 
remedy is only to be found after trying (almost at random) half 
a dozen expedients. 

(9) How Long Should a Tool Run Before Re-grinding f The 
most important conclusions under this heading are: 

It was only after fourteen years' work that we found that the 
best measure for the value of a tool lay in the exact cutting 
speed at which it was completely ruined at the end of 20 minutes. 

If we note the proper cutting speed for a tool which is to 
last 20 minutes, and wish to find the cutting speed for a tool to 
last 40 minutes, multiply the 20-minute cut by 0.92. 

If we have the proper cutting speed for a tool to last 20 
minutes and wish to find the proper cutting speed for a tool to 
last 80 minutes, multiply the 20-minute cut by 0.84. 

The curve approximating the^e values is represented by the 
following formula: 

V = -^ 

T* 

in which 

V = speed of the tool in feet per minute; 

T = length of time tool must last without gnuJing. 

We have been unable to accurately determine the relation 
between the duration of the cut and the cutting speed for tools 
used in cutting cast iron. Such laws are badly needed. 

Modem high-speed tools do a very much larger amount of 
work without re-grinding than carbon-tempered tools. The effect 
upon the cutting speed of the duration of the cut is shown by a 
comparison of modem high-speed tools with carbon tools where 
it was found that the high-speed tools fall off less in their cutting 
speed than the carbon tools, where they are run for a long time. 

We call attention to the fact that as a measure of the value 



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CUTTING TOOLS 81 

of a tool, the length of time which it can be run without being 
re-ground is a false and worthless standard. It is also well to 
note the radically different kind of wear which occurs with tools 
that last only a short while under cut and those which last for 
a longer time. 

(10) Effect of Feed and Depth of Cut on CuUing Speed. The 
following principal conclusions were reached under this heading: 

With any given depth of cut, metal can be removed faster, i.e. 
more work can be done, by using the combination of a coarse feed 
with its accompanying slower speed, than by using a fine feed 
with its accompanying higher speed. 

The cutting speed is affected more by the thickness of the 
shaving than by the depth of the cut. A change in the thickness 
of the shaving has about three times as much effect on the cutting 
speed as a similar proportional change in the depth of the cut 
has upon the cutting speed. Dividing the thickness of the shaving 
by 3 increases the cutting speed 1.8 times; while dividing the 
length that the shaving bears on the cutting edge by 3 increases 
the cutting speed 1.27 times. 

Expressed in mathematical terms, the cutting speed varies 
with our standard round-nosed tool approximately in inverse 
proportion to the square root of the thickness of the shaving or 
of the feed; i.e. S varies with y/F approximately. 

With the best modern high-speed tools, varying the feed and 
the depth of the cut causes the cutting speed to vary in practi- 
cally the same ratio, whether soft or hard metals are being cut. 

(11) Tool Steel and Its. Treatment. The improvements in the 
latest high-speed tools over the originals consist in: 

(a) Far greater uniformity, owing to less danger in being 
injured in grinding and in daily use. 
(6) 50% increase in cutting speed. 

(c) The attainment of almost its maximum cutting speed 
without the necessity of the second or low-heat treatment. 

(d) The combination in the same tool of the highest degree 
of red hardness with a high degree of hardness, thus requiring 
only one standard high-speed tool steel in the shop. 

(e) The ability, owing to increased hardness, coupled with the 
necessary red hardness, to make the same proportionate gain 
when cutting with fine feeds upon hard metals as upon soft. 

(/) Greater strength in the body. 



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82 ENGINEERING AND SHOP PRACTICE 

(g) The only point of inferiority is increased difficulty in 
forging at a cherry-red, and if blacksmiths are taught to forge 
their tools at a light yellow heat, these tools are easier to forge 
than the original high-speed tools. 

(12) Theory of Hardening Steel. 

(13) QualUy of Metal Being Cut. Under this heading we have 
as a broad general guide to the cutting speeds to be used for 
cast iron with the scale on the castings just as they come from 
the foundry, that, as the average of several machine shops in 
this country, it is our observation that medium cast iron may 
be said to belong to Class 18 to 19 in our scale of hardness, and 
that when cutting with a standard Y tool of the quality of steel 
tool of No. 1, with a standard 20-minute cut, a fV depth of cut 
and tV'' feed, they have a cutting speed of 60 feet per minute. 
On the whole, what may be called the hardest castings frequently 
met with in machine shops are not harder than Class No. 24, 
giving a standard cutting speed of 35 feet per minute; while 
softer castings quite frequently met with are as soft as Class 
No. 11, and have a standard cutting speed of 120 feet per minute. 

(14) Line or Curve of Cutting Edge. 

(15) Slide Rules. It may seem strange to say that a slide 
rule enables a good mechanic to double the output of a machine 
which has been run, for example, for ten years by a first-class 
machinist, having exceptional knowledge of and experience with 
his machine, and who has been using his best judgment. Yet 
our observation shows that, on the average, this understates the 
fact. 

427. Tests of High-speed Tool Steels on Cast Iron. Abstract 
from pamphlet issued by the Illinois Engineering Experiment 
Station at the University of Illinois. 

The shape of the tool used in the tests is shown in Fig. 427a. 
The front clearance was 12J°, the top rake was 10° and the side 
rake was also 10°. Experiments relating to the proper shape of 
tools have been made by Prof. J. T. Nicholson, and the writers 
were guided in selecting proper tool angles l)y the recommendations 
of his paper. 

Variation of Cutting Force with Area of Cut. The effort exerted 
by the tool in cutting was determined as explained before. The 
horse-power lost in driving the lathe and countershaft was 
deducted from the total horse-power used during the trial, the 



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CUTTING TOOLS 



83 



difference being the net horse-power used for cutting. This was 
reduced to foot pounds per minute and divided by the cutting 
speed, giving the force exerted. The figures so obtained were 
reduced to pounds per unit area of cut and plotted as ordinates 
upon a base of area of cut. See Fig. 4276. The curves show 
that the cutting force was not directly proportional to the area 
of cut but decreased as the area increased, and that the average 
cutting force varied from 50 tons per square inch for soft cast 
iron, to 85 tons per square inch for hard cast iron. 









Section A-B 



Fig. 427a. 



Section C-D 



Variaiion of Durability of Tool with Cutting Speed, An entirely 
arbitrary standard of durability was established as follows: A 
tool whose cutting edge was worn away .002'' after an hour's 
use was considered perfect, its durability being expressed as 100. 
The ratios of the durability of any other tools to the standard 
will then be the inverse of the ratios of their rates of wear to 
the rate of wear of the standard. 

In Fig. 427c are shown the curves which represent the relation 
between the durability of the tool and the cutting speed. These 
are important curves. Each curve represents a different hardness 
of cast iron. Referring to the middle curve, which is for cast 
iron of medium hardness, it will be seen that a cutting speed of 
50 feet per minute is satisfactory, the durability being 100. If 
the speed is increased very materially, the durability decreases 
quite rapidly. It is evident that for each hardness of cast iron 
the cutting speed allowable for a maximum durability exists 
where the vertical line indicating cutting speed is tangent to 
curves similar to those drawn. 



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84 



ENGINEERING AND SHOP PRACTICE 



Variation of Cutting Speed with the Hardness of Cast Iron. The 
curve shown in Fig. 427d represents the advisable cutting speed 
on cast iron of varying hardness. This curve represents the 
result of all the tests of the different steels tested. This curve 







































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Area of Cut in Square, Inch .^ 

4276. — Curves Showing Relation between Cutting Force on Point of 
Tool and Area of Cut for Cast Iron of Varying Hardness. 



shows: (a) that any of the steels tested can remove very hard 
cast iron at a rate of 25 feet per minute; (b) that all of the steels 
tested begin to wear rapidly at speeds a little above 125 feet per 



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CUTTING TOOLS 



85 



minute. Between these two points the relation between a safe 
cutting speed and the hardness of the cast iron seems to be 
definitely expressed by the curve. It would seem that cast iron 



100 



75 



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Cutting Speed in Feet per Minute 
Fig. 427c. — Curves Showing Variation of Durability of Tool with Cutting 
Speed for Cast Iron of Varying Hardness. 

of medium hardness, 100 to 120, could be cut at 125 feet per 
minute just as readily as at 70 feet per minute, so far as any 
injury to the tool is concerned. It must be remembered that 



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86 



ENGINEERING AND SHOP PRACTICE 



this curve does not take into account the effect, on the cutting 
sf)eed, of the variation in the area of cut; the experiments from 
which the curve was plotted were in all cases those in which the 



8Q0 



"[ 



Curve sbowiuff variation of 
Cutting Speed with Hardness 
of Cast Iron, with results of 
all tool steels. 




25 



123 



50 75 100 

Cutting Speed in Feet per Minute 

Fig. 427d. — Curves Showing Cutting Speeds Best Adapted to Use with 
a Variation in the Hardness of Cast Iron. 

cut was very nearly J" depth of cut by tV" feed, so that there 
is but a slight variation in the area of cut in all of the experiments. 
From the curve of Fig. 427rf we find the cutting speed given in 
the table below to be applicable to the grades of iron manufac- 



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CUTTING TOOLS 



87 



tured by the different companies sending test pieces. In order 
that any company may make use of the curve shown in this 
figure, it will be necessary simply to determine the average 
hardness of its cast iron, as explained elsewhere, and where the 
horizontal line representing this hardness cuts the curve, the 
possible safe cutting speed may be read on the scale below. 



Allowable Cutting Speed for Grades of Cast Iron Used in 
THE Tests 


Average Hardness 
Test Pieces 


Aflowable Cutting 
Speed 


Average Hardness of 
Test Pieces 


AUowable Cutting 
Speed 


101.8 
110.7 
109.3 
112.7 
148.1 


132.0 

118.0 

120.0 

90.0 

60.0 


103.1 

132.0 

343.0* 

175.2 

136.3 


132.0 
63.0 
28.0 
48.0 
60.0 



* Ferro-steel. 

Generally speaking, all the steels tested proved equally effect- 
ive. It is very evident that there are great possibilities ahead 
for the high-speed steels. Before realizing their full benefit, 
however, certain advances must be made. Heavier machine tools 
must be built. The capacity of the motors and power plant must 
be increased. Special hardening furnaces with temperature meas- 
uring devices must be available. More must be known concerning 
the chemical and physical properties of the various steels. 

The following sentences are abstracted from a paper on the 
"New Tool Steel and its Effect on Machine Shop Methods," by 
Prof. C. I. King: "Forgings of 36'' in diameter have been reduced 
to 28^^ at one cut. As a result of this recently acquired knowledge, 
line shaft speeds have been increased from 90 to 250 revolutions 
per minute; cutting speeds are increased 180%, depth of cut 
30%, the rate of feed by 24%, and the end is not yet in sight." 
Professor King predicts planer and shaper speeds of 100 feet per 
minute. 



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88 



ENGINEERING AND SHOP PRACTICE 



428. Revolutions for Given Diameter and Cutting Speeds. 




Cutting Speeds in Feet Per Minute 


Diameter 
Piece 


10 


15 


20 


25 


30 


35 40 


45 


50 


55 


60 


70 


80 


90 




Revolutions Per Minute of Piece 


1 


153 


229 


306 


382 


458 535 611688,764 


840 


I 1 
91^1070,1222 


1376 


i 


102 


153 


204 


255 


306[356 407 


458 509 


560 


612 


712 


814 


916 


i 


77 


115 


153 


191 


229|267 306 


344 382 


420 


458 


534 


612 


688 


1 


61 


92 


122 


153 


183 2141 


244 


275 


306!336'366 


428 


488 


550 


1 


51 


76 


102 


127 


153 


178 


204 


229 255i280!306 


356 


408 


458 


i 


37 


65 


87 
76 


109 
95 


131 
115 


153 


175 


196 
172 


218|240;262 


306 
26S 


350 


392 


1 


38 


57 


134 


153 


19l|210,230 


306 


344 


H 


31 


46 


61 


76 


92 107 


122 


137 153| 1681 184 


214 


244 


274 




25 
22 


38 
33 


51 
44 


64 
55 


76 
65 


89 
76 


102 

87 


114 

'98 


127|l40!l52 
109|l20;i30 


178 
152 


204 
174 


228 
196 


2 


19 


29 


38 


48 


57 


67 


76 


86 


95 


105|ll4 


134 


152 


172 


2i 


15 23 


31 


38 


46 


53 
45 


61 


67 


76 


84 


92 


106 


122 


134 


3 


13 


19 


25| 32 


38 


51 


57 


64 


701 76 


90 


102 


114 


3i 


11 


16 


22 


27 


33 


38 


44 


49 


55 60 66 


76 


88 


98 


4 


9 


14| 19 


24 


29 


33 


38 


43 


48 53 58 


66 


76 


86 


5 


8 


11 


15 


19 


23 


27 


31 34 


38 


42 


46 


54; 62 


68 


6 


6 


9 


13 


16 


19 


22 


25 27 


32 


35 


38 


44 


60 


64 


8 


5 


7 


10 


12 


14 


17 


19 21 


24 


26| 28 


34 


38 


42 


10 


4 


e 


8 


10 


11 


13 


15 


17 


19 


21, 22 


26 


30 


34 


12 


3 


5 


6 


8 


9 


11 


13 


14 


16 


18 18 


22 


26 


28 


14 


3 


4 


5 


7 


8 


9 


11 


12 


14 
12 


15' 16 


18 


22 


24 


16 


2 


4 


5 6 


7i 8 


9| 11 


13 


14 


16| 18 


' 22 


18 


2 


3 


4 5 


6, 7 


8, 9 


11 


12 


12 


14, 16| 18 


24 


1 


2 


3 4 


5 


' 


6 


7 


8 


9 


10 


12 


12 


14 



For greater cuttinR speeds multiply by 2. 
FlQ. 428. 



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CUTTING TOOLS 89 

429. Examples of Recent Practice with High-speed Tool 
Steels. Turning, Milling, Drilling and Planing. 

Turning 





1 




J 


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1 






1 


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1 
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Cast Iron. 


47 


A 


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2.3 


2 


30^ 




1906 


G. M. Camp- 




58 


A 


A 


2.12 


2.2 


42* 




1906 


bell at Penn. 




108 


A 


J 


2.63 


58 


42-^ 




1906 


&L.E. Shops. 


Soft C. Ir. 


















Av.Haitlii. 




















102.8 . . . 


132 


A 


i 


— 


— 






1906 




Av.Hardn. 




















110.7 ... 


118 


A 


i 


— 


— 


16*^ High See Note 


1906 


Illinois. 


Do. 132.0. 


63 


A 


i 


— 


— 


Speed , 




1906 




Do. 138.1. 


60 


A 


i 


— 


— 


Pratt & 




1906 


Eng. 


Do. 175.2. 


48 


A 


i 


— 


— 


Whitney. 




190 


Exp. 


Ferro-Steel 


















Station 


343.0 . . . 


28 
54 


A 


i 


— 


— 






1906 




Wrot. Iron 


A 


4.2 


6.6 30^ 




1906 


Campbell at P. 






i 














A L. E. 


Forged 


32 


H 


33.9 


60 


Armstrong 


A r m - 


1906 


Armstrong & 


Steel . . . 


38 


i 


i 


32.2 


H.P 


& Whit- 


strong 


1906 


Whitworth 




42 


i 


1' 


35.6 


Mo- 


worth Co. 


AWhit- 


1906 


byJ.M.Gled- 




100 


i 


1' 


42.4 


tor 


Special 


worth. 


1906 


hill. 




160 


A 


A 


10.2 




36". 





19C6 












CiT Wheel 






Soft Steel. 


12.5 


A 


1 


6.9 


12.7 


Lathe, 
Axle 


A r m - 
strong 


1906 


G. M. Camp- 
beU at P. & 




43 


A 


A 


3.4 


4.9 


Lathe, 


&Whit- 


1906 


L.Erie Shops. 




04 


»V 


A 


1.9 


3.( 


32" Gis- 
holt. 


worth. 


1906 




Machinery 


48 


i 


A 


6.4 






Mushet. 


1904 


A. Waterman, 


Steel ... 


















Worcester. 


Hani Steel 


13.2 


i 


1 


6.3 


12 


72' Wheel. 




1906 


G. M. Camp- 
beU at P. & 

L. Erie. 



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90 



ENGINEERING AND SHOP PRACTICE 
Turning (continued). 





a 




1 


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1 






1 


£ 
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I 


1 
1 


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a 

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III 

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20 Pt. Car- 


80 


i 


t 


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D. S. & 


Taylor- 


1904 


D2an, Smith & 


bon Steel 


205 


i 


A 


6.1 


— 


Grace, 24^ 


White. 




Grace. 


Siemens- 




















Martin 


















SamOsbomCo. 


Steel.... 


65 


i 


i 


34.5 




32^ Special 


Mushet. 


1906 


England. 


_ . _ 























_ 



Fig. 429o. 

Note. — Generally spoaking, all steels tested proved equally eflFective. 
"Bohler Rapid," Jessup's "Ark," Mclnnesses' "Extra," "Air Novo," 
"Rex," "Poldi" and Armstrong and Whitworth were used. 

Milling 





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Cin.No.4 




Colcord 


Iron. 


59 


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li 


Cin.No.3 
Plain 


<< 


It 


It 


















Phiin 




1905 


Cin. 


tt 


83 


3.7 


ix 1 







i 


H 


Cin.No.2 


Novo 




Mill. 
Mach. 


ti 


90 


27 


^^x3 




3J 


Plain 




Co. 


















Cin.No.3 


it 


u 


ft 



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CUTTING TOOLS 
Milling (continued). 



91 





i 


J 




1 




Cdttkr 


1 


.3 
















1 




J 
■"1 


0^ V 

^1 


0^ 






1 


1 




1 


s 


1 


^1 


a* 


¥ 


1 
5 


2 


1 


1 


1» 


1 


1 


Cast 


130 


36 


ix 1 






Vcrt 


Plain 




15 


Cin. 
Mill 


Iron. 
















Cin.No.2 


- 


- 


Mach. 


Gray 


80 


8 


A3C6J 






8 


Vert, 


Plain 


Co. 


Iron. 


107 


4 






40 


5 





Cin.No.4 


Arm. & 


1906 


<< 


n 


1x6 


305 


Spec. A. & 


A r m - 












H.P. 






Whitw. 


Whitw. 




strong 












Mo- 












k 












tor 










(( 


Whit- 
worth 


Forged 




1.2 


lix7J 


191 


<( 


6 


12 


a 


t( 


ByJ.M. 


Steel. 


75 






382 


<( 


6 








,, 


Gled- 
hiU 


a 


180 


6 


ix 7J 


12 


<< 


'• 


ti 


it 


192 


8- 


ix7i 


157 


<< 


6 


13 


u 


ti 


(< 


tt 



Cutting Speed in Feet per Minute for Surfacing and Slabbing with 

UsoNA Cutters 
Average Depth of Cut i*' 



Material Cut 


Feet per Minute 


Annealed Carbon Steel 


20 


Well Annealed Tool Steel 


40 


Soft Machine Steel, Wrought Iron, Hard White Iron Cast- 
ings, Open Hearth Steel Castings Cast in Dry Sand 
Molds 


60 


Medium Hard Iron Castings, Phosphor Bronze, Tobin and 
Aluminum Bronzes 


60 to 80 


Soft Gray Iron Casting, Malleable Iron Castings, Soft Semi- 
Steel Cast 


70 to 90 


Red Brass 


120 


Yellow Brass 


140 







Fig. 4206. 



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92 



ENGINEERING AND SHOP PRACTICE 



Drilling 









(3 




e 




3 




1 






1 


1 


s 


3 

1 


1 


a 

1-1 

I 

■0 

u 


SB 
< 




*8 


I 

S 
n 


1 


1 


2^ G r a y 






















Arm. & 


Cast Iron 


!5 


129 


630 18 


35 




400 


Good 


A.&W. 


1906 


Whit. 
























byJ.M. 
























GledhiU 


3' G r a y 






















Sam. Os- 


Cast Iron 


J 


140 


725 


17 


42 






it 


Mushet 


1906 


b o r n 
Sheffield 


Wrought 














Wgt.Mctal 








G. M. 


Iron 


2 


20.9 


37 


^i 




1.7 


Removed 
.54 lbs. 
per min. 


(< 




1906 


Camp- 
bell, P. 
& L.E. 
Shops 


i( 


H 


74.5 


228 


^r 




3i 


.52 Wis. 


<( 




1906 


tt 


Tw oT ~J^ 






Max. 












A.&W. 






Steel 






of 










End 


High 






Plates 


\ 


32.5 


Drill 


10.8 


46 




28 holes 


Broke 


Speed 


1906 


tt 


Together 






497 




















i 


48.8 


497 


10.8 46 




50 " 


Good 




1906 


it 




i ; 65 


497 


10.8 


46 




50 " 


n 




1906 


tt 




J j 81.3 


497 


10.8 


46 




50 '' 


ti 




1906 


ti 




} ! 97.6 


497 


10.8 


46 




50 " 


n 




1906 


It 




1 


130.1 


497 


10.8 


46 




50 " 


It 




1906 


tt 


Siemens 






















Sam. Os- 


Steel 






















b o r n 


.30C, 3^ 






















Shef- 


Thick... 


2,\ 


66 


111 


3J 


32 






it 


Mushet 


1906 


field 



FiQ. 429c. 



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CUTTING TOOLS 
Planing 



93 



, 


1 


1 

.s 

1 


J 

3 

1 


1 

5t 


1 

5 


1 


I 
1 


J 


•? 


Cast Iron... 


28.9 


} 


,'. 


18.3 


23.2 


60*^ 




1906 


G. M. Campbell at P. 
& Lake Erie Shops 


it 


37 


A 


ft 


4.6 


4.7 


42' 




1906 




« 


40 


i\ 


ft 


1.46 


2.6 


42" 




1906 




Wrot.Iron.. 


23 


A 


ft 


8.95 


21 


60* 




1906 


" 


tt 


25 


^'l 


i 


4.87 


12.3 


42" 




1906 




tt 


36 


i 


i 


5.7 


7.8 


42' 




1906 




Mach. Steel. 


90 


i 


i 


47 


100 H. P. 
Motor 


42r 


Novo 


1904 


L. P. Exposition, St. 
Louis, Mo. 



Fig 429rf. 

Hand Tools, Grinding and Use 

431. Chisels. 

The Flat or Cold Chisel, This is the most common of all 
machinist's chisels and is often referred to as simply a cold chisel. 
It is generally used whenever any hand chipping or cutting is to 
be done. The cutting edge should be slightly convex with its 
faces ground and whetted at an angle of 60° with each other. 




Fia. 431a. — Flat or Cold Chisel. 



The Cape Chisel, This chisel is similar in its use and action 
to the flat chisel and is most frequently employed in chipping 
keyways, square grooves and where large, flat surfaces are to be 



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94 ENGINEERING AND SHOP PRACTICE 

chipped, for driving a number of grooves across it before using 
the flat chisel. 




4316. — Cape Chisel. 



The Round-nose Chisel, This chisel is used principally for 
grooving oil ways, similar work, and in drilling, to cut out a new 
path for the drill when the hole is improperiy centered. 




Fig. 431c. — Round-nose Chisel 



432. Gravers. Metal turning in the speed lathe is accom- 
plished by means of gravers. Although a speed lathe is used to 
obtain a higher speed for the work, the cutting action of gravers 
depends upon the laws of rake and clearance. They are used 
chiefly for finishing pieces of irregular outline, curves and for 
turning very small pins. As compared with other tools, their 
cutting power is small. Gravers are commonly made from worn- 
out files, preferably those of square section, and their cutting 
edges ground to that particular shape best adapted to the 
work. 

The Diamond-point Graver, This tool is principally used on 
convex surfaces and for rounding comers on such work as the 
end of a bolt or screw. The proper angles of rake and clearance 



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CUTTING TOOLS 95 

are easily determined by noting the chips; to obtain the best 
results the cutting edge should be whetted keen and straight. 

The Round-nose Graver. The principal use of this tool is for 
roughing and for finishing concave surfaces. 




FiQ. 432. — Diamond-point and 
Round-nose Gravers. 

433. Scrapers. Where great accuracy is desired, as it is 
quite impossible to produce a true, plane surface with a planer 
or file, scrapers are resorted to. A scraper is usually a blunt 
chisel-shaped tool with two or more exceedingly hard cutting 
edges, ground with a large (obtuse) angle of keenness. Differ- 
ent forms of scrapers are used for different kinds of work; the 
flat and three-cornered scrapers being the common forms. 
Scrapers are used for truing surfaces and for fitting flat bearing 
surfaces to each other. Errors to be removed by scraping should 
not exceed two or three thousandths of an inch. Scrapers, 
though often made of old files, should be made of the best grades 
of tool steel, as **file steel," when once annealed, can only be 
properly hardened by a special process. Good scrapers may, 
however, be made of old files when no forging is necessary and 
when great care is exercised not to overheat the steel while 
grinding. 

The Flat Scraper. This scraper is the easiest to make, sharpen 
and use, and in expert hands it will remove an astonishing amount 
of surface in a short time. The cutting edge should be drawn 
out to about iV* thick by {{" wide and hardened to the greatest 



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96 



ENGINEERING AND SHOP PRACTICE 



degree. The end is ground slightly convex, like the end of the 
flat chisel, while the sides are ground flat. The end of a scraper 




Fig. 433a. — Flat Scraper. 



should be ground on a wheel of a small diameter in such a manner 
as to produce two cutting edges, 6 and e' (Fig. 433a). In whet- 
ting the faces, / and /', the stone should bear on them; in whet- 
ting the cutting edges, the tool is held in a vertical position so 




Fia. 4336.— Three-cornered Scraper. 



that the edges e and e' rest upon the stone; in this position the 
tool is moved back and forth until sharp. 
The Three-cornered Scraper, See Fig. 4336. 



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CUTTING TOOLS 



97 



Lathe Tools 

441. The Diamond-point Tool. This is the most common cf 
all lathe tools. On account of its shape and owing to its being 
ground with both top and side rake, it easily removes the chip 
and may be used on either roughing or finishing cuts. In adjust- 




FiG. 44L — Diamond- 
point Tool. 

ing the tool, it should be set with just enough clearance to avoid 
friction and as much top rake as the condition will allow. 

442. The Round-nose Roughing Tool. This tool is generally 
used for roughing cuts on cast iron, and sometimes, on account of 
its small amount of top rake, on the softer metals. It is also 
used for turning grooves, rounding out comers, and in many 
places that are inaccessible with the diamond-point tool. 



z> 




Fig. 442. - 
nose Roughing Tool. 

443. The Side Tool. This tool is used for producing the flat 
surfaces in lathe work, such as facing and end turning. To 
obtain the best results, the cutting edge should be slightly convex 
toward the work and whetted keen and smooth. See Fig. 443. 

Note, A right-hand tool is designed to cut from right to left 
and a left-hand tool, vice versa. Water should be used for grinding 
all carbon steel tools. Cutters of self-hardening or tungsten steel 
may be ground dry. 

The Parting or Cutting-off TooL As its name implies, 



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98 ENGINEERING AND SHOP PRACTICE 

this tool is used for partings, for cutting off small pieces of round 
stock; for square grooving and where square comers are desired. 
To work well this tool should be thickest on the cutting edge 



- > J 




53 



ii 



n 



Fig. 443. — Side Tool. 



Fig. 444. — Parting or 
Cutting-off Tool. 



and have ample clearance on all sides. It is generally set on a 
line with the centers. 

445. The Boring Tool. This tool is used for turning the 
inside of cylinders — boring. Its shape and grinding depend 
largely upon the metal to be cut; however, what has been said 
in general about tools will apply. The theoretical height of this 
tool is below the center for the same reason that for outside 
tools it is above the center; for other reasons it is generally placed 
on the center line and ground for scant clearance in this position. 



^ 




^ 




Fig. 445. — Boring Tool. 

446. The Bull-nose Tool. This tool is similar in use and action 
to the diamond point; on account of its shape and rounded cutting 
edge it partakes in a way of the properties of both the diamond 
point and the round nose. It is also used for roughing a facing 
cut. See Fig. 446. 

447. The Threading Tool. U. S. Standard. This tool is used 
for ordinary screw cutting. The 60° angle of the cutting edges 



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CUTTING TOOLS 



99 



should be tested with the center gage for truth, and the point 
ground flat with a width equal to J the pitch of the thread. In 




Fig. 446.— -Bull-nose Tool. 

adjusting the tool, the cutting edges should always be placed in 
a line with the centers, and so that a center line between them 
is perpendicular to the surface on which the thread is to be cut. 




Fig. 447. — Threading Tool, U. S. Standard. 

The angularity of the particular thread to be cut must be taken 
into consideration when grinding for clearance. 

448. The Finishing TooL As the name implies, this tool is 






/lO. 



i 



Fig. 448. — Finishing TooL 

used for taking a finishing cut. It is generally employed on 
large work and where a coarse feed is permissible. 

449. The Brass-working TooL This tool, somewhat similar 




Fig. 449. — Brass-working Tool. 



in shape to the threading tool, is flat on top, has no top rake, 
and is generally ground with more side clearance than the iron 
and steel-working tools. 



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100 ENGINEERING AND SHOP PRACTICE 

Planer Tools 

451. Discussion and Theory. In general, the theory \mder- 
lying all metal cutting tools is the same; and the planer tool 
forms no exception to the rule. The student is advised to review 
what has been said in the discussion of the governing conditions 
of cutting tools in the earlier part of this chapter. 

The most noticeable difference between the grinding of planer 
and lathe tools arises from the fact that the tool-box on planing 
machines is rigid and provides no adjustment for altering the 
angles of top rake and clearance, as does the **rest" of a lathe. 
With planer tools, the shank of the tool is always perpendicular 
to the platen and whatever angles are determined upon must be 
obtained by grinding; the keenness depending upon the angles 
of top rake, side rake and clearance, while the strength depends 
upon the angles of top rake and clearance. The angle of clear- 
ance for planer tools is small, varying from about 3° to 7°. Tools 
for steel and wrought iron have usually a more acute angle of 
keenness than those for cast iron. In some instances roughing 
tools for cast iron have no top rake whatever, keenness being 
obtained by side rake. As was the case in turning, the work is 
finished by the roughing cuts and a finishing cut; the roughing 
cuts being as heavy as the tool and the work will permit; usually 
deep with fine feed. For finishing cast iron, the finishing cut is 
generally very light and made with a broad, square-nosed tool, 
the feed being almost equal to the width of the tool; however, 
for planing surfaces that are subsequently to be scraped, the 
average feed is about ^'', 

For finishing steel or wrought iron, the point of the tool is 
flat, but much narrower than for cast iron. 

452. The Roughing Planer Tool. This tool is similar in shape 
to the round-nose roughing lathe tool and is used for the same 
class of cuts; its general use being for roughing cuts on cast iron 
and sometimes, on account of its small amount of top rake, it 
is also used on the softer metals. Though the general shape of 
this tool remains the same, the contour of the cutting edge and 
the angles of rake and clearance are varied slightly in conformity 
with the nature and depth of the cut and the texture of the 
material. By bending the shank of this tool either to the right 
or to the left, and grinding a straight portion on the cutting 



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CUTTING TOOLS 



101 



edge, we have a tool that is often used instead of side 
tools. 




\J 




Fia. 452. — Roughing Planer Tool. 



453. The Diamond-point Planer Tool. This tool is being 
rapidly superseded by the various roughing tools, because of the 
ease with which they are forged; however, the diamond point, 
on account of its shape and owing to its being ground with both 
top and side rake, easily removes the chip and is used either for 
roughing or finishing cuts. 




Fig. 453. — Diamond- 
point Planer Tool. 

454. The Straight-edge Side Tool (Planer). This tool is used 
for facing and is similar in shape to the side tool used in lathe 



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ENGINEERING AND SHOP PRACTICE 



work, with the exception that the cutting edge, instead of being 
parallel with the shank of the tool, is forged so that it inclines 
toward the back. This lessens the shock when starting the cut, 




Fia. 454. — Straight^ge 
Side Tool, Planer. 

which increases gradually as the tool advances, producing some- 
what of a shearing action and downward pressure, which tends to 
hold the work to the platen. 

455- Slotter Tools. 





Coi-ner 


Square 


Splining 


Hex.for Wrencl 

c >: 


Roughing 


1 


Top 




d4° 


4° 


0° 


8" 


End 


a7« 


aO° 


0° 


a&b4" 


4° 


LSide 


b4° 


b4° 


QJi" 


4° 


4*' 


R Side 


c4« 


4° 


0J« 


4- 


4° 



Fig. 455. — Slotter Tools. 

4S6. Shapes and Grinding of 25 Straight-faced Planer Tools. 

The tables show the various shapes of the common planer 
(Fig. 456) and slotter tools (Fig. 455), and their angles of rake, 
keenness and clearance; the angles herein are taken, in the 
main, from the grinding charts furnished by Wm. Sellers <fe Co., 
and the Gisholt Machine Co., with their universal tool grinders, 
and are fairly indicative of modern practice in this direction. 



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CUTTING TOOLS 



103 



PLANER TOOLS 




Chamfering 



R B^t FiniBh 



L ao Angle 



Side Finish 



Finiahlng 

I n 



18°& 6° 



4" 



be" 



hf 



hi'' 






S' 



do Angle R. 



Spliniug 



3 



Top 



18"& 5" 



End 



4° 



bO" 



LSide 



4*»a4° 



4''b4"' 



«" 



a?" 



L 30^4.8101^ 



L 4S^Angle 



L 40 An?le 



L Bent Sid e Fin 



L Cutting Dowi 



Top 



RSide 



ai'' 



R ao'A Slot 




R Bent Side Fin 



R Cutting Dowi 



Top 



0° 



18°& 6° 



End 



RSide 



Top 



End 



LSlde 



RSide 



a 4*' 



4" 

b4^ 



Rougli Side 



L Side 



Roughing 

n=3 



Cutting Down 

i=2 



Grooving 



16'&»° 



4* 



FiQ. 456. — Planer Tools. 

Tool Holders with Self-hardenino Steel Cutters 

461. Lathe Tools. This style of tool is superseding the hand- 
forged tool for ordinary work for the following reasons: One 
tool and cutter take the place of the diamond-point, round-nose, 
bull-nose and finishing tool. The cutters are made of the finest 
quality of tungsten steel, and being small, and of easily rolled 
sections, cost far less in comparison than a forged tool. Forging 
and tempering are entirely dispensed with, while grinding is 
reduced to a minimum. The cutters may be ground to any 
desired shape or clearance and the cutting edge always keeps at 
the same height. They will work either right or left hand and 
close into a comer. 



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104 



ENGINEERING AND SHOP PRACTICE 




Fia. 461. — Lathe Tool-holder. 



462. Planer Tools. Like similar tools for the lathe, this style 
of tool is superseding the hand-forged tools for ordinary work for 
the same reasons. See Section 461. It is essential that the 
cutter be held rigid, and with the Armstrong holders the cutter 
may be placed at various angles, adapting itself easily to a 




Fig. 462. — Planer Tool-holder. 

variety of work. With this class of holder, reversing it, — i.e., 
placing the cutter in the rear instead of in advance of the 
shank — often prevents gouging and chattering. Later varieties 
of holders provide several cutters, each of which takes its own 
chip, thus multiplying the output by the number of cutters 
used. 



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CHAPTER Y 

MEASURING AND SMALL TOOLS 

Standards of Measurement 

511. Historical Statement A measuring tool is an instru- 
ment or device that is used to compare or measure linear or other 
dimensions with some standard unit. 

The following bit of historical information is taken from the 
Brown & Sharpe catalog: **The Standard Yard was first legalized 
in England in 1824. This standard, however, was destroyed in 
1834. The Standard Imperial Yard, 'Bronze No. 1,' was then 
prepared and legalized in 1855. Forty copies were made; and 
one of these, * Bronze No. 11,' was presented to the United States 
by the British Government in 1856. At the same time another 
copy, known as * Low Moor Iron No. 57, ' was sent. These were 
accurately compared, before being sent, with the Standard 
Imperial Yard, and the record of the variations sent with them. 

** Although the Constitution of the United States empowered 
Congress to fix the standards of weights and measures, no legal 
standard of length was adopted until 1866, when a law was 
passed making the meter legal, the first and only measure of 
length legalized by the United States Government. 

"We prepared standards for use in our own shops, and, after 
their completion, they were compared by the Government officials 
with the standards in Washington. The mean errors were found 
to be: for the yard, .00002'', and for the meter .000006M, both 
being too long." 

Direct Measuring Tools 

521. Rules. The commoner machinist's measuring tools are 
the following: the steel rule, the try square, the micrometer 
caliper, the micrometer caliper square, the bevel protractor, the 
center square and various minor standards called gages. 

The Standard Steel Rule. The most common of all machinist's 

105 



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106 



ENGINEERING AND SHOP PRACTICE 



measuring tools is the standard steel rule. These rules can be 
conveniently introduced into grooves and countersinks of various 
kinds, and are adapted for this class of measurement as well as 
for ordinary use. Owing to the simplicity of the steel rule a 
description is hardly necessary. It may be piu'chased with a 



Miji|i|i|i|i|i|i|i|i|i|l|l|ift|l|i|i|l|l|l|l|i|i|i|i|l|l|i|l|ip rjTTTpF 

^l?l'lililil'lilililil'l'M lil»lliilil.lil 




Fia. 621. — Steel Rule. 

variety of graduations; however, that graduation seemingly best 
adapted for ordinary work is the one having the inches on each 
of the four edges divided respectively into 16ths, 32ds, 64ths 
and lOOths. In direct measurement the lines on the rule are 
made to coincide with the distances measured, while for indirect 
measurement, calipers or dividers — whose points are made to 
coincide with the graduation lines — are used. Great care should 
be exercised in the taking of the finer measurements, as careless- 
ness may lead to the mistaking of one division for another and 
thus ruining the work. 

522. The Try Square. Try squares are used by machinists to 
test the truth and accuracy of surfaces at right angles to each 



r\ 



\j 



■I'v 



^ 



Fio. 522. — Graduated Hardened Steel Square. 

other. No machinist's small shop tool requires more accuracy 
in its construction than does the try square. The stocks and 
edges of the blades are sometimes hardened and in most cases 
are accurately ground for parallelism and for straightness. 

523. The Micrometer Caliper. The micrometer caliper forms 



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MEASURING AND SMALL TOOLS 107 

a convenient and accurate tool for external measurements and is 
used by the machinist for taking accurate measurements on fine 
work. The readings of this tool generally give the dimensions in 






& 



£ 

a 
e 

I 

CO 
M 

6 



thousandths of an inch; however, micrometer calipers may be 
purchased whose readings give the dimensions in ten thousandths 
of an inch. Like most shop tools micrometer calipers are made 
in a variety of sizes and styles, the essential parts being (Fig. 
5236) the micrometer screw or spindle C to which is attached a 
thimble E, the front end of which is beveled and graduated; a 



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108 ENGINEERING AND SHOP PRACTICE 

graduated barrel or sleeve D ; an anvU B on which the work is 
placed for measurement; and a frame A carrying these parts. 

The following principle is the one on which the micrometer 
caliper is based: If a screw of known pitch be turned one revolu- 
tion through its nut^it will have moved a distance equal to the 
pitch of the tnread; if the screw be rotated through a fraction of 
a revolution, its linear motion will be a similar fraction of its 
pitch. Micrometer screws are generally made with forty (40) 
threads to the inch, and have the circumference of the beveled 
edge of the thimble divided into twenty-five (25) equal parts; if 
now the thimble be turned a distance equal to one of these grad- 
uations, the linear motion of the screw will be 5*y of ^ or 
yuV^ inch. The barrel, in which the screw operates and over 



FiQ. 5236. — Micrometer Nomenclature. 

which the thimble fits, is graduated, perpendicularly to the axis 
of the screw, into 40ths of an inch, these divisions being marked 
0, 1, 2, etc., every fourth division. As these graduations conform 
to the pitch of the screw, each division equals the linear distance 
traversed by the screw in one complete revolution, indicating a 
movement of :jV i^^ch. The reading is made by multiplying the 
number of divisions visible on the scale on the barrel by 25, 
adding to this product the number of divisions on the scale on 
the thimble, from the zero graduation to the line coincident with 
the line of graduations on the barrel. These calculations may be 
made mentally: for example, suppose that the number of visible 
graduations of the barrel is 5, and the number of divisions regis- 
tering on the thimble scale is 7. Then 5 X 25 = 125; 125 + 7 
= 132, which is the number of thousandths between the anvil 
and the end of the screw. 



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MEASURING AND SMALL TOOLS 



109 





^A 


h: 


hL 


au [-- 

V 


\k 


"SCI 


MM 




tsi 


"1 1 ■ 


u 


^ 


1 


-1 1 1 



fl 



fl 



I 



Fio. 523c. — Inside Micrometers. 



The method of using the micrometer caliper is as follows: 
Turn the thimble until the micrometer screw (spindle) touches 
the anvil, and note the force required to bring the zero line of 
the thimble in line with the zero line of the barrel (sleeve) ; in the 
taking of fairly correct measurements it will be necessary for 
the student to bring the micrometer screw against the work with 
this same amount of force. The thimble is now turned until the 
screw recedes a somewhat greater distance from the anvil than 



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110 ENGINEERING AND SHOP PRACTICE 

the thickness of the piece to be measured. Placing the piece 
between the anvil and the end of the screw, the thimble is slowly 
revolved until, by the sense of touch, the operator notes that the 
micrometer screw (spindle) is in contact with the work; the reading 
is then taken. Many micrometers are fitted with some sort of a 
locking device which prevents the accidental rotation of the screw. 
In addition to the locking device some micrometers have a ratchet 
stop whereby, if more than a certain degree of pressure is exerted, 
the ratchet slips by the pawl and prevents the turning of the 
screw; this is convenient for the rapid measurement of a number 
of similar pieces as they are all subjected to the same degree of 
pressure. Fig. 523c shows a set of inside micrometers. Such 
micrometers are designed for making internal measurements and 
may be used for measuring rings, cylinder diameters, setting 
calipers, comparing gages, measuring parallel surfaces and work 
of a similar character. Inside micrometers generally consist of a 
micrometer head, carrying the micrometer screw, thimble — 
graduated to read thousandths — and four or more extension 
rods. The rods are provided with a hardened steel adjustable 
anvil in the ends, which permits adjusting for wear. A small 
binding screw locks the rod, when set, to any one of the series of 
lines, — the rods being marked in half-inch or inch divisions and 
set to a similar line on a projection of the barrel. 

524. The Micrometer Caliper Square. By the use of this 
tool the operator is enabled to enlarge or decrease work one or 
more thousandths of an inch from that calipered; this tool em- 
bodies some of the more important features of both the first-class 
caliper square and the micrometer caliper. It may be used as 
a caliper square or a micrometer of large scope and quick adjust- 
ment, or both. As a tool it is less accurate than the micrometer 
caliper on account of the fact that the "personal equation" enters 
into most of its adjustments, as the settings depend largely upon 
the ability of the operator to see accurately. When set to stand- 
ard gages this inaccuracy, of course, disappears. The jaws are 
hardened and ground and open the length of the graduations on 
the beam (generally 4^^, though made in any length), one side of 
which is graduated in 40ths and the other in 64ths of an inch. 
In using this instrument the first setting is made by making the 
graduation mark on the movable jaw coincide with that division 
nearest the size desired; it is then clamped in position. The 



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MEASURING AND SMALL TOOLS 



111 



next step is to loosen the binding screw on the clasp canying the 
micrometer nut, and to turn the nut until the zero mark coincides 
with the graduation line on the clasp; this clasp is then clamped 
in position and the clamp on the movable jaw loosened; the tool 
is now ready for use. When taking a measurement the nut is 
turned while the operator counts the thousandths, adding to or 



1 nJwM^^ 



Fig. 524. — Micrometer Caliper Square. 

taking from the division shown on the beam at the start as 
desired. This tool forms an excellent substitute for use in du- 
plicating work when the number of pieces to be finished does not 
warrant the expense of fixed gages. 

525. The Vernier and Its Use. The following description is 
taken from the catalog of Brown & Sharpe and will, no doubt, 
prove of value in learning the use of the vernier; its application 
is general. 

"On the bar of the instrument is a line of inches numbered 
0, 1, 2, etc., each being divided into ten parts and each tenth 
into four parts, making forty divisions to the inch. On the 



Bar 



.975 
^ .010 on V 
"386 



/• 



10 15 
Vernier 



» 



Fia. 525. — Vernier Reading. 

sliding jaw is a line of divisions (called a vernier from the inventor's 
name) of twenty-five parts numbered 0, 5, 10, 15, 20, 25. (Fig. 
525.) The twenty-five parts on the vernier correspond, in ex- 
treme length, with twenty-four parts or twenty-four fortieths of 
the bar; consequently, each division on the vernier is smaller 
than each division on the bar by one thousandth part of an 



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112 



ENGINEERING AND SHOP PRACTICE 



inch (.001). If the sliding jaw of the caliper is pushed up to 
the other, so that the Hne marked zero (0) on the vernier cor- 
responds with that marked zero on the bar, then the next two 
lines to the right differ from each other by one-thousandth part 
of an inch (.001), and so the difference will continue to increase 
one-thousandth of an inch for each division, until they again 
correspond at the line marked 25 on the vernier. To read the 
distance the caliper may be open: commence by noting how 
many inches, tenths and parts of tenths the zero point on the 
vernier has been moved from the zero point on the bar. Now 
count upon the vernier the number of divisions until one is found 
which coincides with one on the bar, which will be the number 
of thousandths to be added to the distance read off on the bar. 
The best way of* expressing the value of the divisions on the bar 
is to call the tenths one-hundred thousandths (.100), and the 
fourths of tenths, or fortieths, twenty-five thousandths (.025). 
Referring to the cut (Fig. 525) it will be seen that the jaw 
is open two-tenths and three-quarters, which is equal to two 
hundred and seventy-five thousandths (.275). Now suppose the 
vernier was moved to the right so that the tenth division 
should coincide with the next one on the scale — which will 
make ten-thousandths (.010) more to be added to two hundred 
and seventy-five thousandths (.275), making the jaws open two 
hundred and eighty-five thousandths (.285). 

526. The Vernier Calipers. The vernier caliper is so called 
because its readings are taken by means of a vernier instead of 




liliMilililjJili!.iil.'i!tfililililililililJililitililiLlill.lililiLli.l.ililii'lil^ 



Fig. 526. — Vernier Calipers. 



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MEASURING AND SMALL TOOLS 



113 



by means of a micrometer nut. It is similar in almost every 
respect (except in the method of reading its adjustment) to the 
micrometer caliper square. When either of these tools has its 
first setting made by the use of a standard gage, the "personal 
equation" becomes almost nil, and the accuracy then equals that 
of the micrometer caliper. The jaws on both the micrometer 
caliper square and the vernier caliper are so made that internal 
as well as external measurements may be taken. Vernier calipers 
may be purchased with beams 2^" long if so desired. 

527. The Straight-edge. The straight-edge may be termed 
a tool for angular measurement as it is used for measuring angles 
of 180 degrees; i.e, for testing the truth and accuracy of an edge 




Fig. 527o. — Plain Straight-edge. 



1 



Fia. 5276. — Beveled Straight-edge. 



Fig. 527c. — Knife-edge Straight-edges. 



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114 



ENQINEERING AND SHOP PRACTICE 



or plane surface. This is done by placing the tool on the surface 
and noticing that the light comes through the low places. Straight- 
edges are made in three different cross-sections and edges; namely, 
the square edge, the bevel edge and the knife edge, the latter 
being the most accurate. Straight-edges are generally carefully 
hardened on the edges and accurately ground by special machines 
for straightness and parallelism. 

528. The Bevel Protractor, The bevel protractor is used by 
machinists for making angular measurements. As most of these 
measurements are made between surfaces this protractor is 
designed to obtain the desired result by a combination of line 




Fia. 528a. — Universal Bevel Protractor. 

and end measurements. Its essential features are: a graduated 
circle or portion of a circle, in some combination with two straight- 
edges, and a clamping device for retaining the relative position of 
the straight-edges after a setting has been made. Bevel pro- 
tractors may be purchased in a variety of styles and shapes, 
according to the ideas of the manufacturers. A common form 
of bevel protractor has a graduated disc attached to one straight- 
edge, while the other straight-edge carries the indicator, or zero 
line, and the clamping device. One straight-edge is called the 
stock and the other the blade. The blade is from V to 12" long, 
while the stock is V long, and both are made from sheet steel. 
The disc is graduated in degrees from to 90 each way, and rotates 
the entire circle on a central stud inside the case. The blade 
(clamped by an eccentric stud against the edge of the disc) may 



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MKASURING AND SMALL TOOLS 



115 





1 


K> 


J° 


^--- 


^^ 




sU.--...,-,r ■ 




" "-■-■— — ■ « 




^ 


^ 


3 






^\' 1 




I**, 




^ -^ 




L 


ta 


is'-- a. 





\(c^ 




Fig. 5286. — Methods of Using the Universal Bevel Protractor. 

be slipped back and forth its full length, or turned at any angle 
around the circle and firmly clamped at any point, thus adapting 
it for work in positions where other protractors cannot be used and 
thus rendering the common universal bevel (for transferring angles) 
unnecessary. 



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ENGINEERING AND SHOP PRACTICE 



529. Tables. Table of Tapers and Angles, Table of Angles 
of Geometrical Figures. 

Tapers per Foot and Corresponding Angles 



Taper per 
, Fbot 


Included 


Angle with 


Taper per 
Foot 


Included 


Angle with 


Angle 


Center Line 


Angle 


Center Line 


J'^ 


0^36' 


0° 18' 


1 ' 


4° 46' 


2° 23' 


i' 


r 12' 


(f 36' 


IJ' 


7° 09' 


3° 35' 


lY 


1°30' 


0^45' 


ir 


8^20' 


4** IC 


r 


1047. 


0^54' 


2 " 


9° 31' 


4° 46' 


A-' 


2*>05' 


1*»02' 


2Y 


11^54' 


5° 67' 


. i" 


2^23' 


10 12' 


3 ' 


14° 15' 


7^08' 


r 


3° 59' 


1*» 30' 


31' 


16^36' 


8° 18' 


•i^ 


3^35' 


1°47' 


4 -^ 


18^55' 


9*»28' 


i' 


4^ IC 


2*^05' 


5' 


22** 37' 


11-'18' 


ir 


4^28' 


r 14' 


e-' 


26^34' 


13' 17' 



Fig 529a. 

Table for Dividing Circles or Laying Out Geometrical Figures 

See Fig. 529c 



No. of 
Sides 


Included 
Angle 


Angles at Center of Circles 


Angles for Sides of Figures 


3 


120° 


30° 


30° 


4> 


90° 


45° 


45° 


5 


72° 


18°, 54° 


36°, 72° 


6 


60° 


30° 


30° 


8 


45° 


45° 


22° 30' 


10 


36° 


54°, 18° 


18°, 54° 


12 


30° 


60° 


15°, 45° 


14 


25° 43' 


64° 17', 38° 34', 12° 51' 


12° 51', 38° 34', 64° 17' 


16 


22° 30' 


6r 30', 45° 


11° 15', 33° 45' 


18 


20° 


70°, 50°, 30°, 10° 


10°, 30°, 50°, 70° 


20 


18° 


72°, 54° 


9°, 27°, 45° 


24 


15° 


75°, 60°, 45° 


7° 30', 22° 30, 37° 30' 



Fig. 5296. 



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MEASURING AND SMALL TOOLS 



117 




Fig. 529c. ^ Diagram Illustrating Table, Fig. 5296. 

Gages 

531. Classification. Gages for linear dimensions may be 

divided into dimensional and numbered gages, according to 

whether they measure a portion of the unit length or express a 

size by some arbitrary letter or number. 

Dimensional Gages 
541. Test and Reference Gages. Test or reference gages are 
used chiefly to test the accuracy of other instruments and gages, 



;/ 




Fig. 541. — End Measure Teet Pieces. 



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118 ENGINEERING AND SHOP PRACTICE 

and vary in form in accordance with the maker's ideas. Standard 
end measures are made either circular or rectangular in section, 
with the end surfaces parallel 4nd standard within a limit of 
accuracy of ^xyivir ^^ ^^ ^^c^- They are accurate subdivisions of 
the Imperial Yard and are valuable for determining the accuracy 
of micrometers, slide or beam gages and "snap" gages. Refer- 
ence discs are shaped like a silver dollar, their circular form 
making them very convenient for setting calipers. Very accurate 
measurements may be made with this form of gage as a very 
delicate contact is obtained, since the gage and piece are only 
in line contact with each other. 

542. Standard Cylindrical Gages. This class of working gages 
is recommended for the most accurate work, and possesses large 




Fia. 642. — Cylindrical Gage and Plug. 

wearing surfaces which are hardened, ground and lapped accu- 
rately to size; and on account of the warranted accuracy to y^yj^^ 
of an inch the gages are interchangeable. They are made for 
both internal and external measurements. 

543. Standard Caliper Gages. In the smaller sizes of this 
gage the external gage is at one end and the internal gage at the 
other. In construction they are light, rigid and are intended for 
general shop work. Pratt & Whitney state that it has been 
clearly demonstrated and proved conclusively that the limit of 
delicacy of touch in regard to calipering or duplicating parts 
required to be interchangeable is about ^jii^jf of an inch, and in 
no other gage is this minute difference so perceptible as with a 
*'snap" (caliper) gage having parallel jaws, hardened, ground 
and polished, thus making this an available practical ** instrument 
of precision," necessary in every machine shop where interchange- 
able work is demanded. 



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MEASURING AND SMALL TOOLS 



119 





Fia. 543. — Standard Caliper Gages. 

544. Limit Gages. Limit gages are used primarily as time- 
savers to avoid the waste of time in finishing parts unduly accu- 




h|« 




External 




Internal 

Fig. 544a. — Standard Limit Gages. 

rate, still having them accurate enough to meet all the demands 
of interchangeable manufacture. While other gages give the 



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120 



ENGINEERING AND SHOP PRACTICE 



exact size, no knowledge is had as to the exact amount the piece 
is "out." A limit gage is in fact two gages; thus in the external 
form one, the "go on" is intended to slip over the piece; the 
other, the "not go on," one, not to slip over it, the limit or differ- 
ence in size between the two varying according to the nature of 
the work. Such gages are widely used where the accurate and 
economical production of duplicate parts is essential; for by their 
use the time consumed in testing and gaging is reduced to a 
minimum, while the parts are still finished accurately enough to 
have them go together sufficiently well to obviate the necessity 




Fio. 5446. — Adjustable Limit Gages. 

of further fitting. For the limits allowed and the standard limits 
for limit gages the reader is referred to the tables and data on 
"Limits for Limit Gages," Section 788, Chapter 7, "Bench and 
Vise Work." 

Numbered Gages 

551. Criticism. According to the best authorities, a properly 
designed, arbitrary (numbered or lettered) gage should have the 
divisions increase by a regular geometric progression; however, 
this is not the case with the gages now in use. For several 
reasons intelligent men look forward to the time when all arbi- 
trary gages will be abolished and when all dimensions will be 
given in fractions of the unit length. Trautwine makes the 



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MEASURING AND SMALL TOOLS 121 

following pertinent remarks relative to this subject: "No trade 
stupidity is more thoroughly senseless than the adherence to the 
various Birmingham, Lancashire, etc., gages instead of at once 
denoting the thickness and diameter of sheets, wire, etc., by the 
parts of an inch as has been long suggested. To avoid mistakes 
that are very apt to occur from the number of gages in use, and 
from the absurd practice of applying the same gage number to 
different metals in different towns, it is best to ignore them all 
and in giving orders to define the diameter of wire and the thick- 
ness of sheet metal by parts of an inch." 

These arbitrary gages are used to designate the sizes of sheet 
metal, wire, drill rods, screws, etc., and are made in two different 
ways; the notched gage is intended to push over the material 
measured, while with the triangular slotted gage the material 
(usually of circular cross-section) is pushed into the slot until it 
touches both sides, when the division at the point of contact gives 
the gage number. 

In Section 558 will be found tables giving the decimal equiv- 
alents of an inch, corresponding to the various sheet metal, wire, 
drill and screw gages in common use. 

552. The United States Standard Gage. The United States 
standard gage was established by an Act of Congress in 1893; it 
is used by the Government in determining the taxes and duties 
levied on sheet iron, plate iron and steel, and by some American 
rolling mills for the above and American planished iron. 

553. The American or Brown & Sharpe Gage. This gage is 
used almost exclusively for sheet brass, sheet aluminum, sheet 
German silver, brass wire, brazed brass tubing, and German silver 
wire of American manufacture. 

554. The Birmingham or Stubs' Wire Gage. In using 
Stubs' gages it should be remembered that a difference exists 
between Stubs' iron wire gage and Stubs' steel wire gage. The 
Birmingham, the English standard wire and Stubs' wire are the 
same, and are w^idely used for sheet iron, sheet steel, sheet copp)er 
and seamless tubing of all kinds. Stubs' steel wire gage is used in 
measuring drawn steel wire or drill rods of Stubs' make. 

555. The Washburn & Moen Mfg. Go's Gage. This gage is 
used almost entirely for gaging the products of this company. 

556. The American Twist Drill Gage. This gage is used by 
American manufacturers for the smaller sizes of twist drills. 



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ENGINEERING AND SHOP PRACTICE 



557. The American Screw Gage, and Others. This gage is 
used almost exclusively for wood and machine screws of iron, 
steel or brass and designates the size of the unthreaded portion 
of the shank, regardless of the style of the head. 

Among the numerous other gages may be mentioned: The 
steel music wire gage, the Illinois Zinc Go's zinc gage, the Russia 
iron gage and the decimal gage. 

558. Comparison of Wire, Sheet Metal, and other Gages. 





Dimensions in Dectmal Fractions op an Inch 




Number 

of 

Gage 


Birming- 
ham or 
Stubs' 
Iron Wire 
Gage 


American 

or 

Brown 

& Sharpe 

Gage 


Roebling' s 
and Wash- 
bum & 
Mocn's 
Gage 


Trenton 
Iron 
Co.'s 
Wire 
Gage 


British Imperial Std. 

Wire Gage Legal Sid. 

in Gr. Br'fn since 

Mar. I. 1884 


U.S. Std. 

Gage for 
Sheet and 
Plate Iron 
and Steel 
Ugal Std. 
since July 
1,1893 


Number 

of 

Gage 




Inches 


MilU- 
meters 




0000000 






.49 




.500 


12.7 


.5 


7/0 


000000 






.46 




.464 


11.78 


.469 


6/0 


00000 






.43 


.45 


.432 


10.97 


.438 


5/0 


0000 


.454 


.46 


.393 


.40 


.4 


10.16 


.406 


4/0 


000 


.425 


.40964 


.362 


.36 


.372 


9.45 


.375 


3/0 


00 


.38 


.3648 


.331 


.33 


.348 


8.84 


.344 


2/0 





.34 


.32486 


.307 


.305 


.324 


8.23 


.313 





1 


.3 


.2893 


.283 


.285 


.3 


7.62 


.281 


1 


2 


.28 


.25763 


.263 


.265 


.276 


7.01 


.261 


2 


3 


.259 


.22942 


.244 


.245 


.252 


6.4 


.25 


3 


4 


.238 


.20431 


.225 


.225 


.232 


5.89 


.234 


4 


5 


.22 


.18194 


.207 


.205 


.212 


5.38 


.219 


5 


6 


.203 


.16202 


.192 


.19 


.192 


1.88 


.203 


6 


7 


.18 


.14428 


.177 


.175 


.176 


4.47 


.188 


7 


8 


.165 


.12849 


.162 


.16 


.16 


4.06 


.172 


8 


9 


.148 


.11443 


.148 


.145 


.144 


3.66 


.156 


9 


10 


.134 


.10189 


.135 


.13 


.128 


3.26 


.141 


10 


11 


.12 


.09074 


.12 


.1175 


.116 


2.95 


.125 


11 


12 


.109 


.08081 


.105 


.105 


.104 


2.64 


.109 


12 


13 


.095 


.07196 


.092 


.0925 


.092 


2.34 


.094 


13 


14 


.083 


.064C8 


.08 


.08 


.08 


2.03 


.078 


14 


15 


.072 


.05707 


.072 


.07 


.072 


1.83 


.07 


15 


16 


.065 


.05082 


.063 


.061 


.064 


1.63 


.0625 


16 


17 


.058 


.04526 


.054 


.0525 


.056 


1.42 


.0563 


17 


18 


.049 


.0403 


.047 


.045 


.048 


1.22 


.05 


18 


19 


.042 


.03589 


.041 


.04 


.04 


1.01 


.0438 


19 


20 


.035 


.03196 


.035 


.035 


.036 


.01 


.0375 


20 


21 


.032 


.02846 


.032 


.031 


.032 


.81 


.0344 


21 



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MEASURING AND SMALL TOOLS 



123 





Dimensions in Decimal Fractions or an Inch 




Number 

of 

Gage 


Birming- 
ham or 
Stubs' 
Iron Wire 
Gage 


or Brown 

& Sharpe 

Gage 


RoebUng's 

and Wafh 

bum & 

Moen's 

Gage 


Trenton 

Iron Co.'s 

Wire 

Gage 


British Imperial Std. 

Wire Gage Legal Std. 

in Gr. Britain since 

March i, 1884 


U.S. Std. 

Gage for 
Sheet and 
Plate Iron 

and Steel 

Legal Std. 

since July 

», 1893 


Number 

of 

Gage 




Inches 


MilU- 
meters 




22 


.028 


.02535 


.028 


.028 


.028 


.71 


.0313 


22 


23 


.025 


.02257 


.025 


.025 


.024 


.61 


.0281 


23 


24 


.022 


.0201 


.023 


.0225 


.022 


.56 


.025 


24 


25 


.02 


.0179 


.02 


.02 


.02 


.51 


.0219 


25 


26 


.018 


.01594 


.018 


.018 


.018 


.45 


.0188 


26 


27 


.016 


.01419 


.017 


.017 


.0164 


.42 


.0172 


27 


28 


.014 


.01264 


.016 


.016 


.0148 


.38 


.0156 


28 


29 


.013 


.01126 


.015 


.015 


.0136 


.35 


.0141 


29 


30 


.012 


.01002 


.014 


.014 


.0124 


.31 


.0125 


30 


31 


.01 


.00893 


.0135 


.013 


.0116 


.29 


.0109 


31 


32 


.009 


.00795 


.013 


.012 


.0108 


.27 


.0101 


32 


33 


.008 


.00703 


.011 


.011 


.01 


.25 


.0094 


33 


34 


.007 


.0063 


.01 


.01 


.0092 


.23 


.0086 


34 


35 


.005 


.00561 


.0095 


.0095 


.0084 


.21 


.0078 


35 


36 


.004 


.0C5 


.009 


.009 


.0076 


.19 


.007 


36 



Fio. 558a. 

Table of Decimal Equivalents of Screw Gage for Machine and 

Wood Screws 

The diflference between consecutive sizes is .01316''. 



No. of 


Size of Number 


No. of 


Size of Number 


No. of 


Size of 
Number in 
Decimals 


Screw Gage 


in Decimals 


Screw Gage 


in Decimals 


Screw Gage 


000 


.03152 


16 


.26840 


34 


.50528 


00 


.04468 


17 


.28156 


35 


.51844 





.05784 


18 


.29472 


36 


.53160 


1 


.07100 


19 


.30788 


37 


.54476 


2 


.08416 


20 


.32104 


38 


.55792 


3 


.09732 


21 


.83420 


39 


.57108 


4 


.11048 


22 


.34736 


40 


.58424 


6 


.12364 


23 


.36052 


41 


.59740 


6 


.13680 


24 


.37368 


42 


.61056 


7 


.14996 


25 


.38684 


43 


.62372 


8 


.16312 


26 


.40000 


44 


.63688 


9 


.17628 


27 


.41316 


45 


.65004 


10 


.18944 


28 


.42632 


46 


.66320 


11 


.20260 


29 


.43948 


47 


.67636 


12 


.21576 


30 


.45264 


48 


.68952 


13 


.22892 


31 


.46580 


49 


.70268 


14 


.24208 


32 


.47896 


50 


.71584 


15 


.25524 


33 


.49212 







Fig. 5586. 



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124 



ENGINEERING AND SHOP PRACTICE 



Decimal Equivalents of the Numbers of Twist Drill and Steel 

Wire Gage 



No. 


Size of 
Number in 
Decimals 


No. 


Size of 
Number in 
Decimab 


No. 


Size of 
Number in 
Decimals 


No. 


Size of 
Number in 
Decimals 


1 


.2280 


21 


.1590 


41 


.0960 


61 


.0320 


2 


.2210 


22 


.1570 


42 


.0935 


62 


.0380 


3 


.2130 


23 


.1540 


43 


.0890 


63 


.0370 


4 


.2090 


24 


.1520 


44 


.0860 


64 


.0360 


5 


.2055 


25 


.1495 


45 


.0820 


65 


.0350 


6 


.2040 


26 


.1470 


46 


.0810 


66 


.0330 


7 


.2010 


27 


.1440 


47 


.0785 


67 


.0320 


8 


.1990 


28 


.1405 


48 


.0760 


68 


.0310 


9 


.1960 


29 


.1360 


49 


.0730 


69 


.02925 


10 


.1935 


30 


.1285 


50 


.0700 


70 


.0280 


11 


.1910 


31 


.1200 


51 


.0670 


71 


.0260 


12 


.1890 


32 


.1160 


52 


.0635 


72 


.0250 


13 


.1850 


33 


.1130 


53 


.0595 


73 


.0240 


14 


.1820 


34 


.1110 


54 


.0550 


74 


.0225 


15 


.1800 


35 


.1100 


55 


.0520 


75 


.0210 


16 


.1770 


36 


.1065 


56 


.0465 


76 


.0200 


17 


.1730 


37 


.1040 


57 


.0430 


77 


.0180 


18 


.1695 


38 


.1015 


58 


.0420 


78 


.0160 


19 


.1660 


39 


.0995 


59 


.0410 


79 


.0145 


20 


.1610 


40 


.0980 


60 


.0400 


.80 


.0135 



Fig. 558c. 

Small Tools — Various Gages 

S6i. The Screw Pitch Gage. A screw pitch gage is a tool 
similar in shape to a pocket-knife; its blades are notched to con- 
form with the sections of standard threads so that they will fit 
standard screws having a certain number of threads per inch. 
This tool is used to measure the threads of nuts as well as that 
of screws. On each blade is stamped the number of notches, 
that is threads per inch, and twice the depth of the thread; this 
latter amount subtracted from the outside diameter of the screw 
gives the size for the tap drill. 

562. The Center Gage. The center gage is generally a short 
notched steel rule, similar in shape to the conventional represen- 
tation of the feathered end of an arrow. It is used in grinding 
and in setting screw cutting or threading tools. The angles used 



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MEASURING AND SMALL TOOLS 



125 



on the standard gage are 60 degrees for the United States standard 
thread. The four graduations on this gage have the inch divided 
into 14, 20, 24 and 32 parts, which are convenient in measuring 



ttPltcbes 




Fig. 561. — Screw Pitch Gage. 

the number of threads per inch of ordinary taps aud screws; 
however, all center gages are not graduated and marked alike. 
Some gages have a table which is used to determine the size of 
tap drills for *'V" threads, giving in thousandths of an inch 



FIG.3 




VvWvWvW 
vVvWvVv 




lAl 



Fig. 562. — Center Gage and Method of Using it. 



twice the depth of the thread of the common pitches. This 
amount subtracted from the diameter of the screw gives the 
diameter of the tap drill for a "V" thread. Such a table for 



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126 



ENGINEERING AND SHOP PRACTICE 



United States standard threads may be made by dividing the 
constant 1.299 — twice the depth of a thread of a screw that is 
one pitch — by the number of threads for each desired pitch. 
The use of this gage is illustrated and taken up at length in 
Section 876. 

563. The Depth Gage. A depth gage is a simple tool used 
for measuring the depth of holes, keyways and recessed parts, as 



o 



Fig. 



563. — Depth Gage. 



well as for measuring distances under a shoulder or small pro- 
jections on a plane surface. The blade or rod generally passes 
through the head at right angles to it and may be clamped when 
the setting is made. 

564. The Universal Surface Gage. A surface gage is a tool 
used by machinists for measuring off distances, usually from a 
given plane surface. It is chiefly used in setting work prepara- 
tory to machining it. The principal parts of a universal surface 
gage are a solid base with clamping and adjustment devices, a 
post which may be turned through an arc of 270 degrees, a swivded 
sleeve carrying a scriber clasp which may be swung around the 
post ; a scriber clasp for holding the scriber on the swi veled sleeve 
and a scriber for making the markings. (Fig. 564a.) 



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MEASURING AND SMALL TOOM 



127 




Fia. 664a. — Universal Surface Gage. 

The base is grooved so that it may be placed on cylindrical 
surfaces. Minute adjustment may be made after the scriber 
point is set to the approximate height by turning the knurled 
adjustment nut, usually located in the base. Fig. 5646, page 
128, illustrates the use of this tool. 

Small Tools — Ordinary Kit 

571. Arbors or Mandrels. An arbor is generally a shaft or 
spindle for driving into a bored portion of a piece, the outside of 
which is to be turned between lathe centers. The term " mandrel " 
is commonly applied to the same tool. The commercial solid 
arbor is made of tool steel, hardened and ground, and tapers 
about j^jf" per foot from the smaller end, which is generally 
exact size, though some are made a trifle. under size. The larger 
end bears the stamp which designates the nominal size, and both 



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128 ENGINEERING AND SHOP PRACTICE 



3 



Fig. 5646. — Methods of Using the Universal Surface Gage. 




Fig. 571a. — Hardened and Ground Steel Mandrel. 



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MEASURING AND SMALL TOOLS 129 

ends of such an arbor are turned slightly under size with a flat- 
tened portion to receive the dog. The end surfaces are slightly 
rounded so that the bumping and hammering which they receive 
will not destroy the truth of the countersunk centers; this class 
>f arbor is designed to hold work reamed by standard reamers. 




Fio. 5716. — Nicholson Expanding Lathe Mandrel. 



Expanding arbors or mandrels are generally made with a 
sleeve and taper, and are designed to hold any work, the bore of 
which is within their capacity. An arbor should be driven or 
pressed into the bore just tight enough to prevent slipping; any 
further forcing tending to distort the piece, thus producing inac- 
curate work. 

• 572. Reamers. A reamer is a tool designed for truing and 
making accurate drilled holes which are rarely found to be round 
and straight. A standard type of reamer consists of a round 
piece of tool steel, a portion of which contains straight or spiral 
flutes lengthwise, producing cutting edges, which are hardened 
and accurately ground to size. The ends of the cutting edges 
are made slightly rounded or tapered, producing in the reamer a 
tendency to keep toward the center of the hole. The tapered 
portion of the cutting edge is sometimes threaded, producing 
what is called a self-feeding reamer. The end of the shank is 




Fig. 572a. — Self -feeding Reamer. 

provided with a squared portion by means of which the reamer 
may be turned. Other varieties of reamers that may be men- 
tioned are fiat, chucking and shell reamers, for use in turret 
machinery; roughing and finishing taper reamers for reaming 
standard taper holes; expanding or adjustable reamers for obtain- 



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130 ENGINEERING AND SHOP PRACTICE 

ing a minute variation in the size of the holes; and center reamers 
for reaming coimtersunk centers. 

Holes under I'' in diameter, that are subsequently to be reamed, 
should be drilled or bored ^^ under size; for holes over I'' and 
under 2" in diameter ^'^ of stock is left for the reamer to remove, 
the holes being made ^^ under size. For very accurate work 
the reamer should always be operated by hand and the method 
of securing the alignment of a tap may be successfully used for 
reaming. A center is inserted in the drill spindle, and this, 
inserted in the countersink in the end of the reamer, is used to 



Fig. 5725. — Shell Reamers. 




Fig. 572c. — Shell Reamer Arbor. 

secure the alignment, the reamer being turned by means of a 
tap wrench as usual. 

573. Calipers. A pair of calipers is a tool with two adjustable 
legs for taking or transferring measurements. Outside calipers 
are made with curved legs and, as the name implies, are used for 
taking outside measurements, while inside calipers have straight 
legs and are used for inside measurements. Calipers are set to 
*'gage" or to ''scale"; they are hardly to be considered as instru- 
ments of precision as the setting or the taking of measurements 
are dependent upon the skill and sense of touch of the operator. 
In setting calipers to scale, care should be taken to have one 
leg flush with the end of the scale, adjusting the other leg by 
means of the thumb nut until it splits the line; as the average 
thickness of the line is .0025'', an error of this amount is often 
suflicient to spoil accurate work. In taking measurements the 
calipers must be placed squarely across the piece, at right angles 



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MEASURING AND SMALL TOOLS 131 

to the portion measured; any deviation — side play — from this 
position resulting in inaccurate measurements. 



Fia. 573a. — Outside and Inside Spring Calipers. 

Hermaphrodite calipers have one leg pointed like a divider 
leg and the other similar to the leg of an inside caliper. 

574. Dividers. A pair of dividers is a tool resembling an 
ordinary pair of compasses and is used by the machinist for 
dividing and describing various lines and circumferences. The 
points of the legs are hardened for scratching metal surfaces and 
the adjustments are made similar to the adjustments of calipers. 
Dividers are used extensively in laying out drill and lathe work. 

575. Scribers. A scriber is a machinist's marker or scratch 
awl, a standard form of which consists of a cylindrical knurled 
stock or sleeve with two fine, hardened steel points, one of which 
is bent at right angles to the axis of the tool. 

576. Center Punches. A center punch is a tool similar in 
size and shape to a nail set, with the point hardened and ground 
conical. It is used by the machinist for indicating by dots the 
location of various lines and centers. Before being struck with 
the hammer, it is held peipendicular to the surface to be marked. 



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132 ENGINEERING AND SHOP PRACTICE 






I 



CO 

2 



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MEASURING AND SMALL TOOLS 



133 



Fig. 674. — Spring Dividers. 



FiQ. 575. — Sleeve Scriber. 



^rrrj 



a 



a 



d 



cr 



v^J>i/sS f f^fr '^ 4, ■ «■• tjgj^y '■ ^.ij 



^*»i..iWft^T>»..Wt,-^..^lTt..l 




FiQ. 576. — Center Punches. 



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134 ENGINEERING AND SHOP PRACTICE 

The location of any mark may be slightly changed by slanting 
the punch in the direction towards which it is desired to move 
the mark. 

577. Wrenches. Wrenches are tools used by machinists for 
turning various nuts and screws; they are made in a variety of 
designs and sizes. Wrenches may be divided into the following 
general classes: 

Movable jaw wrenches, designed for turning different sized 
nuts; the common monkey wrench being the best example of 
this class. 

Fixed jaw wrenches are drop-forged or cast wrenches, the 
distance between whose jaws is fixed. 

Socket wrenches are T-shaped wrenches, designed for turning 
bolts or nuts below the surface. 

Spanner wrenches are designed for turning cylindrical nuts. 

Pipe wrenches with hardened jaws are used for gripping and 
turning various sized pipe and cylindrical pieces. 

Tap and reamer wrenches, as their names indicate, are used 
for turning taps and reamers; they are made adjustable and with 
double handles. 



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CHAPTER VI 

SCREW AND PIN DATA 

Screw Parts 

6ii. Nomenclature. It is important for any one who has 
to do with the manufacture of screws and screw threads to un- 
derstand fully the exact meaning of the following terms: Pitch, 
Lead; Threads per inch and Turns per inch. 

612. Pitch. In its strictest sense and in the sense in which 
it should always be used in referring to screw threads, "pitch" 
is the distance from the center of one thread to the center of the 
next thread, measured in a line parallel to the axis of the screw. 
The "threads to the inch" and "thread pitch" are reciprocals of 
each other (the reciprocal of a number is 1 divided by that 
number). 

613. Lead. The "lead" of a screw is the distance the thread 
advances in one turn. In a single-threaded screw the lead and 
pitch are the same; in a double-threaded screw the lead is twice 
the pitch, while in a triple-threaded screw the lead is three times 
the pitch. 

614. Threads per Inch. The term "threads per inch" means 
the number of coils to an inch; however, the term threads per 
inch has nothing whatever to do with the number of separate 
grooves or windings. The pitch is the reciprocal of the threads 
per inch. 

615. Turns to an Inch. The " turns to an inch " is the number 
of advances the thread makes in one inch and is the number 
obtained by dividing one inch by the lead; that is, the reciprocal 
of the lead of a screw is the turns per inch. 

A thread may be triple-threaded, i" pitch, f * lead, 8 threads 
to the inch, and have 2^ turns to an inch. 

135 



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VM 



KSntSKKHSSn ASf) HUOV I'RArmCK 



H^MNlMfCfl TaPH ami DtVM 

63 1 « Standard Tapi* A iu(i i^ a hauUttuul nUti*] wmWf fluted 
hufpUuUtuiWy to form (flitting (^J^fft, atul having at the end of 
itN nhank a H/|uari*^l jMiiiJon, over whi^^h Im fifU^J the tap wreneh 
l>y wlii'^h it i^ Uirtuul, The r;ornnion forrrm rrf tafw are the tafxjr, 
the phiK find the iKfttoniing taf>; the general ehara^;teriHticM of 
eaeh may Int note<l from Fig, 021, 




Fio. 02i. liiind Tii|)M, TiijiiT, PIuk and Dottoniing. 

The taper tap in \mul for threading holen whieh paHH clear 
tlirongh the material. Where it \h deNJrc'd to thread a hole that 
doeH not run through the pi(?ce, the taper tfip \h UMOil to Htart the 
thread, the plug tap to complete it to near the bottom, and 
Hhould a full thread all the way to the bottom of the hole be 
re(|uired, the bottoming tap mtmt be UHe<l. 

Tapri and dieH are made to cut the '^Htandard thread^' and are 
made in Mi/,eM given in the tabhj " IJ. H. Standard Hcnjw-Thread 
Holt and Nut Data/' (Fig. 071.) l<or formulan, tap drilln and 
any other data relative to U. H. Htandard threadH, the readier iH 
n»ferred to thin table. 

6aa. Machine Screw Tape. Machine Hcrew tapH are made 
with "V" threjidM and are UMcd for tapping holcn for machine 



Vm, (VZ2. MiicliiiM' ScH'W Tap. 



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SCREW AND PIN DATA 



137 



screws which are generally less than {" in diameter. As yet no 
national standard for machine screw sizes and threads has been 
established; see Sec. 676. Machine screw taps, like standard 
hand taps, are made taper, plug and bottoming with the shanks, 
either the size of the bottom of the thread, or full thread size. 

A rough and ready method of determining the size of tap 
drills for machine screw taps is to insert the point of the tap in 
a drill gage and select a drill that will make a hole a trifle larger, 
say jijf". The tables in Section 672 give the decimal equivalents 
for the nominal sizes of tap drills for machine screw taps. 

623. Dies or Screw Plates. Dies or screw plates are hardened, 
steel-threaded nuts, fluted across the thread so as to form cutting 




Fia. 623a. — Adjustable Dies. 

edges, and having such a shape as to be easily fastened in holders 
called stocks, by which they are turned. 




Fig. 6236. — Machine or Solid Bolt Dies. 



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138 



ENGINEERING AND SHOP PRACTICE 



624. Standard Pipe Taps and Dies. Pipe taps and dies are 
made to conform with the Briggs' standard of threads for wrought- 
iron welded tubes, and taper i" to the foot. In Section 673 
is given a table of standard dimensions of wrought-iron welded 
pipe according to the Briggs standard, which is now in gen- 
eral use and was formally adopted by the Manufacturers of 
Wrought-iron Pipe and Boiler Tubes in the United States, at 
their Pittsburg meeting in 1886. 




Reamer 



Hob 
Fig. 624. — Pipe Tap, Hob and Reamer. 

Screws 

631. Machine Screws. Machine, cap, and set screws are 
made in a variety of sizes and heads. Machine and wood screws 
are made in sizes corresponding to the American screw gage; 
the difference between consecutive sizes is .01316'', starting with 



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SCREW AND PIN DATA 



139 



No. 000 which is .03152'^, and ending with No. 50, the size of 
which is .71584.'^ The diameter of the screw in inches is obtained 
by the formula D = .01316 (AT + 2) + .03153, where N equal 
the screw number. In the A.S.M.E. Standard Proportions for 




No. I 



No.J 





No. 3 No. 4 

Fig. 631. — Machine Screws. No. 1, Flat Head. 
No. 2, Round Head. No. 3, Oval Fillister Head. 
No. 4, Oval Countersunk or French Head. 

Machine Screws " The uniform increment between all sizes from 
.060* to .190^ is .013'' and between .190* and including .450* is 
.026*. This conforms approximately to the list of screw gage 
sizes originally estabUshed in which the increment is .01316." 
" This evidently avoids impracticable final decimals and forms 
a series in which the sizes have a definite relation to each 
other." "The pitches are a function of the diameter as ex- 

6 5 
pressed by the formula, Threads per inch = , , ^^(^9 ^^d the re- 
sults are given approximately and in even numbers in order to 
avoid the use of fractional or odd number threads." The 



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140 



ENGINEERING AND SHOP PRACTICE 



angle of the cone of flat-head (countersunk) screws is 76° old 
style and 82° A.S.M.E. Standard, the sides making angles of 
52° old style and 49° A.S.M.E. Standard with the top. 

The commoner heads on machine screws are termed flat heads, 
round heads, flat fillister heads and oval fillister heads. Ma- 
chine screws are made with ''V" or U. S. Standard threads as 
desired. For further information consult the tables and data in 
Section 676. 

632. Cap Screws. The diameter of cap screws is generally 
stated in fractions of an inch. They, like machine screws, are 
made with a variety of heads such as square head, hexagon head, 
oval filjister head and flat fillister head, flat head, button head 
and oval countersunk or French head. Cap screws are usually 




Fia. 632. — Cap Screw. 

made with the U. S. Standard thread, and on all screws one inch 
or less in diameter, and less than four inches long, the threads 
are cut three quarters of the length; beyond four inches threads 
are cut half the length. For dimensions of heads and other data 
consult the table of standard cap and set screwTS. Section 675. 
633 Set Screws. The diameter of set screws, like that of 
all other bolts and screws except machine screws, is stated in 



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SCREW AND PIN DATA 



141 



fractions of an inch. Set screws may be purchased with the 
U. S. standard or **V" threads and are always case-hardened, if 
made of iron, or tempered, if made of steel. They are threaded 
clear up to the head, which latter, if there be one, is always 
square. The following terms designate the peculiar character- 
istics of the commoner set screws: cup point, round point, flat 
point, cup point headless, round point headless, cone point head- 
less, flat pivot point, round pivot point, hanger set point, cone 




No. II No. 2 'No. 6 

Fig. 633. — Set Screws. No. 1, Regular Round Point. No. 2, Cup Point. 
No. 3, Flat Point. No. 4, Cup Point Headless. No. 5, Round Point Head- 
less. No. 6, Cone Point Headless. No. 7, Flat Pivot Point. No. 8, Round 
Pivot Point. No. 9, Hanger Set Point. No. 10, Cone Point. No. 11, 
Not Necked. 

point and not necked. Cup point set screws are regular, all other 
kinds are special, and no screw which has a head more than ^^ 



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142 ENGINEERING AND SHOP PRACTICE 

larger than the body is classed as a set screw. See Section 675 
for other data regarding set screws. 

634. Coach or Lag Screws. Coach or lag screws are large 
wood screws with a head designed to be turned with a wrench; 
they are made with either square or washer heads. 



No. I No. 2 No 3 

Fig. 634. — Coach Screws. No. 1, Square Head Fia. 635. — Hanger 
Gimlet Point. No. 2, Washer Head Gimlet Point. Screw. 

635. Hanger Screws. Hanger screws are similar to coach 
screws with the exception that a nut is provided instead of a head. 

Bolts and Studs 

641. Machine Bolts. Machine bolts are made U. S. standard 
with square or hexagon heads and are threaded, on the longer 



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SCREW AND PIN DATA 143 

bolts, for a distance equal to three times their diameter. Tap 
bolts are similar to machine bolts with the exception that they 
are threaded clear up to the head. 



No.i No.2 

i?'ia. 641. Machine Bolts. — No. 1, Square Head, Square 
Nut Machine Bolt. No. 2, Hexagon Head, Hexagon 
Nut Machine Bolt. 

642. Coupling Bolts. Coupling bolts are made similar to a 
hexagon-headed machine bolt, with the exception that the thick- 
ness of the head equals the diameter of the bolt and that the 



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144 



ENGINEERING AND SHOP PRACTICE 



bolts are machined to size under the head; they are used in the 
various shaft couplings. 

643. Carriage Bolts. Carriage bolts are made with a squared 
portion directly underneath the head, which latter is never square 




N0.4 No.s 

Fig. 643. — Carriage Bolts. No. 1, Common Carriage Bolt. No. 2, Ova! 
Head Philadelphia Eagle Carriage Bolt. No. 3, Bevel Head Philadel- 
phia Eagle Carriage Bolt. No. 4, Bastard Head Philadelphia Eagle Car- 
riage Bolt. No. 5, Countersunk Head Philadelphia Eagle Carriage Bolt. 

or hexagon. They are furnished with square nuts and are made 
with the following heads: common, oval, bevel, bastard and 
countersunk. 



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SCREW AND PIN DATA 145 

644. Stove Bolts. Stove bolts are made with flat countersunk 
or round heads, and are furnished with large, thin square nuts; 
they are principally used for stove work. 

645. Studs. A stud is a piece of steel or iron threaded at 
both ends with an unthreaded portion in the middle; that portion 
which is threaded to receive the nut is rounded on the end, while 

ABC 




Fia. 645. — Milled Iron Stud. 

the portion intended to be screwed into the casting is faced flat; 
the standard length of the threaded portion being IJ times the 
diameter of the screw. Studs are used for bolting heads and 
flanges to cylinders, or in details where the piece is likely to be 
removed several times during the life of the machine. 

Nuts, Rivets, Cotters, Etc. 

651. Nuts. A nut is that square- or hexagon-shaped piece of 
steel with a threaded hole designed to screw on a bolt or stud. 
Nuts are made in the U. S. standard sizes and may be pur- 
chased rough punched, rough threaded, semi-finished, finished 
and case-hardened. 

652. Rivets. Rivets are manufactured of extremely ductile 
and malleable material and should be able to withstand severe 
treatment in forging without impairing their strength. They 
are made with various heads such as flat, round, bevel, cone, 
machine, globe, countersunk, truss, wheel, oval countersunk and 
wagon box. See page 146 for Fig. 652. 

653. Cotters. A cotter is a split pin with an eye head, de- 
signed to be inserted in a drilled hole. 




FiQ. 663. — Spring Cotter. 



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146 ENGINEERING AND SHOP PRACTICE 



I Bevel Head 



Truss Head 



Wheel Head 



Id 



Globe Head Wagon Box Head Oval Countersunk Head 

FiQ. 652. — Rivete. 



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SCREW AND PIN DATA 



147 



654. Washers. A washer is a thin annular piece of sheet 
steel designed to fit under the nut or head of a bolt. 

655. Burrs. A burr is a special washer designed to fit over 
the shank of a rivet. 

656. Tumbuckles. A tumbuckle is a double-ended sleeve or 
nut with right and left threads; it is used in guy and tension rods 
for shortening their length. 




c 





Fia. 656. -- Tumbuckles. 



Pin Data 



661 • Dowel and Taper Pins. Whenever it is necessary in 
the assembling of machine parts to preserve an alignment, dowels 
or taper pins are used. Holes are drilled in the pieces, and when 
the parts are assembled and aligned these holes are reamed with 
a taper reamer and taper pins fitted into them. The best com- 
mercial taper pins are hardened and ground and taper J'' per 
foot. Both reamers and pins are so designed that each size 
"overlaps" the size smaller about i^ in length; the taper being 
the same, the advantage thus secured is obvious. 



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148 ENGINEERING AND SHOP PRACTICE 

Tabulated Bolt and Thread Data. 
671. XT. S. Standard Thread, Bolt and Nut Data. 



< 

h 
3 
Z 

O 
Z 
< 

O 

m 

d 

< 
u 
oc 

z 

o 
oc 

< 

z 
< 

H 
(0 

(0 

Ui 

^ 

(0 

o 
u 

z 

3 



I 






li 



H 



i-e 



& 

I. 



Is IS 

!l SI 



US 



3 



lift 



iU 



III 



ilt 



MJ 



3}3 






J|! 



dShar 



ZoOS 






iliil 



oSsi 3338 



iSsipss: 



iu 



lilil 



»§!§§. SSicS 



jj+^+ij.. 



mm 



iit 



]l 



liiiHlIi! 



UJt 






|L4 









iLi 

Ui 



Ui 



5;f?5w5?:5J^5. 



1 j?L± +• I +± 



^^ wi^f? 



ifn?s3e 



fill 



nil iiii 



»»is 



:f::5 



ills 



gss§ gssi 



KISS i^§9 



tiiiaii 



llli 



«is»s 



f+++ f I++ 



lipi 



III! Iiii nil 

iiiiiiii 



5«Sil 



Sill 



mn 



immmu 



iiSBgs|§§|i!| 



<$sis§lil 



8SSI21i| 



iSli 



iiii 



Iiiiiiii 



8||j8 



Sill llli 



SS8&§igi| 



nil 



im 






C-3- «*.<• 5 <•< 



MMMM ««««0 



?5?S 



iiii 



111! 



»«« 






=iBi 



iS: 



^? 



iii^ 



S3§l SSSSi 



»«R 






Ilii 



iiii nil 






lai 



ills 



ill iiii 



ill 



sKk 



iiiillllliii 



'tS=sS 



mmkum 



\m mi mn 



.«99 



llli 



pi? 

iiiiiibipi 



•m 



iiii 



Awkff 



m 



im 






11 [ill 



llliii 



iiiiiiii 



llli 



2SS 



lillill 



mm 



mmm 



mm \ 



iillllilllll 



mm 



iBmll 



llli 






2 



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SCREW AND PIN DATA 



149 



672. Tap and Thread Data for Machine Screws. 

Decimal Equivalents of Nominal Sizes of Tap Drills for Machine 
Screws (Old Style Std.) 



Diam. 
In. 


Pilch. 


Exact 
Diam. 
Bot. of 
Th'd. 


Amcr. 
DriU 


Diam. 


Si« 


Approx. 
Sizes in 

Frac. 

of In. 


Std. No. 


Amer. 
Drill 


Diam. 


Thread 
per In. 


Gage. 

No. Tap 

Drill 


Tap DriU 
in In. 


Screw 
Gage 


of 
Th'ds. 


Gage. 

No. of 

TapDrill 


Tap Drill 
in In. 


A 


60 


.041 


57 


.0430 













t". 


64 


.042 


56 


.0465 


1 


A 








A 


48 


.067 


50 


.0700 


2 


A 


56 


46 


.0810 


A 


50 


.068 


50 


.0700 


3 




48 


47 


.0785 


A 


56 


.071 


49 


.0730 


4 


ii 


36 


43 


.0890 


A 


60 


.072 


48 


.0760 


5 




36 


38 


.1015 


i 


40 


.093 


41 


.0960 


6 


A 


32 


37 


.1040 


J 


44 


.096 


40 


.0980 


7 




32 


30 


.1285 


i 


48 


,098 


39 


.0995 


8 


A 


32 


29 


.1360 


A 


32 


.116 


31 


.1200 


9 




30 


26 


.1470 


A 


36 


.120 


31 


.1200 


10 


A 


24 


26 


.1470 


A 


40 


.124 


30 


.1285 


11 




24 


20 


.1610 


A 


24 


.133 


29 


.1360 


12 


1 
12 


24 


19 


.1660 


A 


28 


.141 


27 


.1440 


13 




22 


16 


.1770 


A 


30 


.144 


26 


.1470 


14 


i 


20 


14 


.1820 


A 


32 


.147 


25 


.1495 


15 




20 


10 


.1935 


A 


36 


.152 


23 


.1540 


16 


« 


18 


7 


.2010 


A 


24 


.164 


19 


.1660 


17 




18 


4 


.2090 


A 


28 


.172 


16 


.1770 


18 


\l 


18 


1 


.2280 


A 


32 


.178 


14 


.1820 


19 




18 


D 


.2460 


A 


36 


.183 


12 


.1890 


20 


A 


16 


E(l) 


.2500 


i 


18 


.178 


14 


.1820 


22 




16 


H(H) 


.2660 


i 


20 


.185 


11 


.1910 


24 


i 


16 


L 


.2900 


i 


22 


.190 


10 


.1935 


26 




16 


P(ii) 


.3230 


i 


24 


.196 


8 


.1990 


28 




14 


R (H) 


.3390 


i 


26 


.200 


6 


.2040 


30 


A 


14 


T (iJ) 


.3580 



Fig. 672a. 



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150 



ENGINEERING AND SHOP PRACTICE 



672b. Standard Machine Screws. A.S.M.E. Standard. 



Basic and Maximum Screw Diameters 


Minimum Screw Diameters 


External Diam. and 
No. Th'ds per In. 


Pitch 
Diameter 


Root 
Diameter 


External 
Diameter 


Pitch 
Diameter 


Root 
Diameter 


.060—80 


.0519 


.0438 


.0572 


.0505 


.0411 


.073—72 


.064 


.0550 


.070 


.0625 


.052 


.086—64 


.0759 


.0657 


.0828 


.0743 


.0624 


.099—56 


.0874 


.0758 


.0955 


.0857 


.0721 


.112—48 


.0985 


.0839 


.1082 


.0966 


.0808 


.125-^4 


.1102 


.0955 


.1210 


.1082 


.0910 


.138-^0 


.1218 


.1055 


.1338 


.1197 


.1007 


.151—36 


.1330 


.1149 


.1466 


.1308 


.1097 


.164—36 


.146 


.1279 


.1596 


.1438 


.1227 


.177—32 


.1567 


.1364 


.1723 


.1544 


.1307 


.190-30 


.1684 


.1467 


.1852 


.166 


.1407 


.216—28 


.1928 


.1696 


.2111 


.1903 


.1633 


.242—24 


.2149 


.1879 


.2368 


.2123 


.1807 


.268—22 


.2385 


.209 


.2626 


.2358 


.2013 


.294—20 


.2615 


.229 


.2884 


.2587 


.2208 


.320—20 


.2875 


.255 


.3144 


.2847 


.2468 


.346—18 


.3099 


.2738 


.3402 


.3070 


.2649 


.372—16 


.3314 


.2908 


.366 


.3284 


.281 


.398—16 


.3574 


.3168 


.392 


.3544 


.307 


.424—14 


.3776 


.3312 


.4178 


.3745 


.3204 


.450—14 


.4036 


.3572 


.4438 


.4005 


.3464 



Fig. 6726. 

The pitches are a function of the diameter, as expressed by 
the formula, threads per inch = 

6.5 
D + 0.02 

and the results are given approximately and in oven numbers in 
order to avoid the use of fractional or odd number threads. 



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SCREW AND PIN DATA 



151 



673. Standard Dimensions of Wrought-iron Welded Pipe. 



Diameter of Pipe 






ScxEWBO Ends 








Thickness of 

the Metal, 

Inches 


Dmmeter of 
the Tap Drill, 






Nominal In- 


Actual In- 


Actual Out- 


Number of 
Threads 


Length of 


side. Inches 


side. Inches 


side, Inches 






per Inch 


Inches 


i 


.270 


.405 


.068 


U 


27 


.19 


i 


.364 


.504 


.088 


a 


18 


.29 


i 


.494 


.675 


.091 


il • 


18 


.30 


i 


.623 


.840 


.109 


a 


14 


.39 


i 


.824 


1.050 


.113 


a 


14 


.40 


1 


1.048 


1.315 


.134 


lA 


111 


.51 


H 


1.380 


1.660 


.140 


HI 


111 


.54 


li 


1.610 


1.900 


.145 


Iff 


111 


.55 


2 


2.067 


2.375 


.154 


2A 


Hi 


.58 


2J 


2.468 


2.875 


.204 


2H 


8 


.89 


3 


3.067 


3.500 


.217 


^z 


8 


.95 


3J 


3.548 


4.000 


.226 




8 


1.00 


4 


4.026 


4.500 


.237 




8 


1.05 


4J 


4.508 


5.000 


.246 




8 


1.10 


5 


5.045 


6.563 


.259 




8 


1.16 


6 


6.065 


6.625 


.280 




8 


1.26 


7 


7.023 


7.625 


.301 




8 


1.36 


8 


7.982 


8.625 


.322 




8 


1.46 


9 


9.000 


9.688^ 


.344 




8 


1.57 


10 


10.019 


10.750 


.366 




8 


1.68 



Fig. 673 

Note. — Taper of conical ends, 1 in 32 to axis of tube, or a total t-aper 
of i" per foot. 

1 Changed to 9.625 by Manufacturers of Wrought Iron Pipe and Boiler Tubes. 



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152 



ENGINEERING AND SHOP PRACTICE 



674. Table of Decimal Equivalents of an Inch. 

The following table (Fig. 674) of decimal equivalents of an 
inch will prove useful in many instances and is here inserted to 
assist in the selection of various drills. 



Decimal 


8ths 


i6ths 


32<l8 


64ths 


Decimal 


8ths 


i6ths 


3 ads 


64ths 


.015625 








1 


.515625 








33 


.03125 






1 




.53125 






17 




.046875 








3 


.546875 








35 


.0625 




1 






.5625 




9 






.078125 








5 


.578125 








37 


.09375 






3 




.59375 






19 




.109375 








7 


.609375 








39 


.125 


1 








.625 


5 








.140625 








9 


• .640625 








41 


.15625 






5 




.65625 






21 




.171875 








11 


.671875 








43 


.1875 




3 






.6875 




11 






.203125 








13 


.703125 








45 


.21875 






7 




.71875 






23 




.234375 








15 


.734375 








47 


.25 


2 








.75 


6 








.265625 








17 


.765625 








49 


.28125 






9 




.78125 






25 




.296875 








19 


.796875 








51 


.3125 




5 






.8125 




13 






.328125 








21 


.828125 








53 


.34375 






11 




.84375 






27 




.359375 








23 


.859375 








55 


.375 


3 








.875 


7 








.390625 








25 


.890625 








57 


.40625 






13 




.90625 






29 




.421875 








27 


.921875 








59 


.4375 




7 






.9375 




15 






.453125 








29 


.953125 








61 


.46875 






15 




.96875 






31 




.484375 








31 ; 


.984375 








63 


.5 










One inch 


8 


16 


32 


64 



Fig. 674. 



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SCREW AND PIN DATA 



153 



675. Standard Set Screws and Cap Screws. 
Thread. (CoinpUcd by W. S. Dix.) 



XT. S. Standard 





A 


B 


C 


D 


E 


F 


G 


Diameter of Screw 


i 
40 


A 


20 


A 


} 


A 


i 


Threads per Inch 


24 


18 


16 


14 


12 


Size of Tap DriU (Cast Iron) 


No. 43 


No. 3( 


) No. 5 


a 


a 


i 


« 




H 


I 


J 


K 


L 


M 


N 


Dijunetpr of Screw 


A 
12 


1 

11 

H 


1 

10 

li 


i 
9 


1 

8 


7 


li 
7 


Thrpada oer Inch 


Size of Tap DriU (Cast Iron) 


i» 


• Set Sceews | 


Hexagon-Head Cap Screws 


Square Head Cap Screws 


Short 
Diam. 
Head 


Long 
Diam. 
Head 


Lengths 
(Under 
Head) 


Short 
Diara- 
Head 


Long 
Diam. 
Head 


Lengths 
(Under 
Head) 


Short 
Diam. 
Head 


Long 
Diam. 
Head 


Lengths 
(Under 
Head) 


(C) i 


.35 


i to3 


A 


.51 


f to3 


1 


.53 


i to3 


(D) ft 


.44 


ito3i 


i 


.58 


}to3i 


ft 


.62 


}to3i 


(E) i 


.53 


ito3i 


A 


.65 


|to3i 


i 


.71 


ito3i 


(F) ft 


.62 


}to3} 


t 


72 


}to3i 


ft 


.80 


ito3i 


(G) i 


.71 


} to 4 


i 


.87 


} to4 


1 


.89 


} to 4 


(H) ft 


.80 


ito41 


15 


.94 


ito4i 


H 


.98 


ito4i 


(I) 1 


.89 


}to4i 


i 


1.01 


1 to4i 


i 


1.06 


1 to 4} 


(J) i 


1.06 


1 to 4} 


1 


1.15 


li to 4} 


i 


1.24 


li to 4i 


(K) i 


1.24 


li to6 


li 


1.30 


IJ to 5 


U 


1.60 


li to 5 


(L)l 


1.42 


IJ to5 


li 


1.45 


1} to6 


11 


1.77 


li to5 


(M)U 


1.60 


1} to 6 


i| 


1.59 


2 to 5 


i| 


1.95 


2 to 5 


(N)li 


1.77 


2 to 5 


li 


1.73 


2 to 5 


li 


2.13 


2i to 5 


ROOND AND FiLLISTEK HeAD 
CAr SCKEWS 


Flat-Head Cap Screws 


Button-Head Cat Screws 


Diam. o( 
Head 


Lengths 
Under Head 


Diam. of 
Head 


Lengths 
Including Head 


Diam. of 
Head 


Lengths 
Under Head 


(A) ft 


}to2i 


i 


itoli 


ft (.225) 


itoli 


(B) i 


ito2} 


1 


} to2 


ft 


i to2 


(C) 1 


i to3 


n 


|to2i 


ft 


ito2i 


(D) ft 


}to3i 


i 


ito2i 


ft 


ito2J 


(E) ft 


ito3i 


i 


}to3 


) 


ito2i 


(F) 1 


ito3i 


li 


1 to 3 


I 


i to3 


(G) } 


} to 4 


i 


li to3 


\i 


1 to 3 


(H) « 


1 to4i 


1 


li to3 


\i 


li to3 


(I) I 


lito4j 


11 


li to3 


1 


li to3 


(J)l 


lito4} 


i| 


2 to 3 


li 


li to3 


(K)li 


li to6 










(L)U 


2 to 5 











Fig. 675. 



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154 



ENGINEERING AND SHOP PRACTICE 



676. Standard Machine Screw Proportions and Other Data. 

Table of Standard Machine Screws. Old Standard. (Compiled 

BY W. S. Dix) 



*No. 


Threads 
per In. 


Diam. of 
Body 


Diam. of 
Flat Head 


Diam. of 
Round Head 


Diam. of 

Fillister 

Head 


Lengths 


From 


To 


2 


56 


.0842 


.1631 


.1544 


.1332 


A 




3 


48 


.0973 


.1894 


.1786 


.1545 


A 




4 


32, 36, 40 


.1105 


.2158 


.2028 


.1747 


A 




5 


32, 36, 40 


.1236 


.2421 


.2270 


.1985 


A 




6 


30,32 


.1368 


.2864 


.2512 


.2175 


A 




7 


30,32 


.1500 


.2947 


.2754 


.2392 






8 


30,32 


.1631 


.3210 


.2936 


.2610 






9 


24, 30, 32 


.1763 


.3474 


.3238 


.2805 






10 


24, 30, 32 


.1894 


.3737 


.3480 


.3035 






12 


20,24 


.2158 


.4263 


.3922 


.3445 






14 


20,24 


.2421 


.4790 


.4364 


.3885 




2 


16 


16, 18, 20 


.2684 


.5316 


.4866 


.4300 




2} 


18 


16,18 


.2947 


.5842 


.5248 


.4710 




2i 


20 


16,18 


.3210 


.6368 


.5690 


.5200 




2} 


22 


16,18 


.3474 


.6894 


.6106 


.5557 




3 


24 


14,16 


.3737 


.7420 


.6522 


,6005 




3 


26 


14,16 


.4000 


.7420 


.6938 


.6425 




3 


28 


14,16 


.4263 


.7946 


.7354 


.6920 




3 


30 


14,16 


.4520 


.8473 


.7770 


.7240 


1 


3 



Lengths vary by 16ths, from A to }, by 8ths from } to li, by 4ths 
from 1} to 3. 

FiQ. 676a. 



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SCREW AND PIN DATA 



155 



A.S.M.E. Standard Machine Screw Proportions 



Old 


New 


Outside Diametess 


Pitch Diametkks 


Root Diameters 


No. 


Out.Dia.and 


Mini- 


Maxi- 


DiflFcr- 


Mini- 


Maxi- 


Differ- 


Mini- 


Maxi- 


Differ- 




Thds.P.I. 


mum 


mum 


ence 


mum 


mum 


ence 


mum 


mum 


ence 





.060—80 


.0572 


.060 


.0028 


.0505 


.0519 


.0014 


.0410 


.0438 


.0028 


1 


.073—72 


.070 


.073 


.003 


.0625 


.064 


.0015 


.052 


.055 


.0030 


2 


.086—64 


.0828 


.086 


.0032 


.0743 


.0759 


.0016 


.0624 


.0657 


.0033 


3 


.099—56 


.0955 


.099 


.0035 


.0857 


.0874 


.0017 


.0721 


.0758 


.0037 


4 


.112—48 


.1082 


.112 


.0038 


.0966 


.0985 .0019 


.0807 


.0849 


.0042 


6 


.125—44 


.1210 


.125 


.0040 


.1082 


.1102 


.0020 


.0910 


.0955 


.0045 


6 


.138-40 


.1338 


.138 


.0042 


.1197 


.1218 


.0021 


.1007 


.1055 


.0048 


7 


.151—36 


.1466 


.151 


.0044 


.1308 


.1330 


.0022 


.1097 


.1149 


.0052 


8 


.164—36 


.1596 


.164 


.0044 


.1438 


.146 


.0022 


.1227 


.1279 


.0052 


9 


.177—32 


.1723 


.177 


.0047 


.1544 


.1567 


.0023 


.1307 


.1364 


.0057 


10 


.190—30 


.1852 


.190 


.0048 


.166 


.1684 


.0024 


.1407 


.1467 


.0060 


12 


.11^—28 


.2111 


.216 


.0049 


.1904 


.1928 


.0024 


.1633 


.1696 


.0063 


14 


.242—24 


.2368 


.242 


.0052 


.2123 


.2149 


.0026 


.1808 


.1879 


.0071 


16 


.268—22 


.2626 


.268 


.0054 


.2358 


.2385 


.0027 


.2014 


.209 


.0076 


18 


.294—20 


.2884 


.294 


.0056 


.2587 


.2615 


.0028 


.2208 


.229 


.0082 


20 


.220—20 


.3144 


.320 


.0056 


.2847 


.2875 


.0028 


.2468 


.255 


.0082 


22 


.346—18 


.3402 


.346 


.0058 


.3070 


.3099 


.0029 


.2649 


.2738 


.0089 


24 


.372—16 


.366 


.372 


.0060 


.3284 


.3314 


.0030 


.281 


.2908 


.0098 


26 


.398—16 


.392 


.398 


.0060 


.3544 


.3574 


.0030 


.307 


.3168 


.0098 


28 


.424—14 


.4178 


.424 


.0062 


.3745 


.3776 


.0031 


.3204 


.3312 


.0108 


30 


.450—14 


.4438 


.450 


.0062 


.4005 


.4036 


.0031 


.3464 


.3572 


.0108 



Fig. 6766. 



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Google 



156 



ENGINEERING AND SHOP PRACTICE 



Special Screws. A^.M.E. Standard 



Old 


New 




Pitch Diameters 


Root Diametkrs 


No. 


Out.Dia.and 


Mini- 


Moxi- 


Differ- 


Mini- 


Maxi- 


Differ- 


Mini- 


Maxi- 


Differ- 


Thds.P.I. 


mum 


mum 


ence 


mum 


mum 


ence 


mum 


mum 


ence 


1 


.073—64 


.0698 


.073 


.0032 


.0613 


.0629 


.0016 


.0494 


.0527 


.0033 


2 


.086—66 


.0825 


.086 


.0035 


.0727 


.0744 


.0017 


.0591 


.0628 


.0037 


3 


.099—^8 


.0952 


.099 


.0038 


.0836 


.0855 


.0019 


.0677 


.0719 


.0042 


4 


.112--40 


.1078 


.112 


.0042 


.0937 


.0958 


.0021 


.0747 


.0795 


.0048 




36 


.1076 


.112 


.0044 


.0918 


.094 


.0022 


.0707 


.0759 


.0052 


6 


.125-40 


.1208 


.125 


.0042 


.1067 


.1088 


.0021 


.0877 


.0925 


.0048 




36 


.1206 


.125 


.0044 


.1048 


.107 


.0022 


.0837 


.0889 


.0052 


6 


.138-36 


.1336 


.138 


.0044 


.1178 


.120 


.0022 


.0967 


.1019 


.0052 




32 


.1333 


.138 


.0047 


.1154 


.1177 


.0023 


.0917 


.0974 


.0057 


7 


.161—32 


.1463 


.151 


.0047 


.1284 


.1307 


.0023 


.1047 


.1104 


.0057 




30 


.1462 


.151 


.0048 


.1270 


.1294 


.0024 


.1017 


.1077 


.0060 


8 


.164—32 


.1593 


.164 


.0047 


.1414 


.1437 


.0023 


.1177 


.1234 


.0067 




30 


.1592 


.164 


.0048 


.1400 


.1424 


.0024 


.1147 


.1207 


.0060 


9 


.177—30 


.1722 


.177 


.0048 


.1529 


.1553 


.0024 


.1277 


.1337 


.0060 




24 


.1718 


.177 


.0052 


.1473 


.1499 


.0026 


.1158 


.1229 


.0071 


10 


.190—32 


.1853 


.190 


.0047 


.1674 


.1697 


.0023 


.1437 


.1494 


.0057 




24 


.1848 


.190 


.0052 


.1603 


.1629 


.0026 


.1288 


.1359 


.0071 


12 


.216—24 


.2108 


.216 


.0052 


.1863 


.1889 


.0026 


.1548 


.1619 


.0071 


14 


.242—20 


.2364 


.242 


.0056 


.2067 


.2095 


.0028 


.1688 


.1770 


.0082 


16 


.268 -20 ; .2624 


.268 


.0056 


.2327 


.2355 


.0028 


.1948 


.203 


.0082 


18 


.294—18', 2882 


.294 


.0058 


.255 


.2579 


.0029 


.2129 


.2218 


.0089 


20 


.320-18 


.3142 


.320 


.0058 


.281 


.2839 


.0029 


.2389 


.2478 


.0089 


22 


.346-16 


.340 


.346 


.0060 


.3024 


.3054 


.0030 


.255 


.2648 


.0098 


24 


.372—18 


.3662 


.372 


.0058 


.333 


.3359 


.0029 


.2909 


.2998 


.0089 


26 


.398—14 


.3918 


.398 


.0062 


.3485 


.3516 


.0031 


.2944 


.3052 


.0108 


28 


.424—16 


.418 


.424 


.0060 


.3804 


.3834 


.0030 


.333 


.3428 


.0098 


30 


.450—16 


.444 


.450 


.0060 .4064 


.4094 


.0030 


.359 


.3688 


.0098 



Fig. 6766 {continued). 



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SCREW AND PIN DATA 



157 




Fig. 676c. Flat Head Screws. 
AS.M.E. Standard 

A = Diameter of Body 

B = 2A - .008 = Diameter of Head 

C - ^^^-^ = Thickness of Head 

D = .173A + .015 - Width of Slot 
E = JC « Depth of Slot 



A 


B 


C 


D 


E 


.060 


.112 


.030 


.025 


.010 


.073 


.138 


.037 


.028 


.012 


.086 


.164 


.045 


.030 


.015 


.009 


.190 


.052 


.032 


.017 


.112 


.216 


.060 


.034 


.020 


.125 


.24? 


.067 


.037 


.022 


.138 


.268 


.075 


.039 


.025 


.151 


.294 


.082 


.041 


.027 


.164 


.320 


.090 


.043 


.030 


.177 


.346 


.097 


.046 


.032 


.190 


.372 


.105 


.048 


.035 


.216 


.424 


.120 


.052 


.040 


.242 


.476 


.135 


.057 


.045 


.268 


.528 


.150 


.061 


.050 


.294 


.580 


.164 


.066 


.055 


.320 


.632 


.179 


.070 


.060 


.346 


.684 


.194 


.075 


.065 


.372 


.736 


.209 


.079 


.070 


.398 


.788 


.224 


.084 


.075 


.424 


.840 


.239 


.088 


.080 


.450 


.892 


.254 


.093 


.085 



Fig. 67ec. 



Digitized by 



Google 



158 



ENGINEERING AND SHOP PRACTICE 



FiQ. 676d. Round Head Screws. 
A.S.M.E. Standard 

A «» Diam. of Body 

B = 1.85A- .005. - Diam. of Head 

C « .7A = Height of Head 

D « .173A + .015 = Width of Slot 

E = JC + .01 - Depth of Slot 




A 


B 


c 


D 


E 


.060 


.106 


.042 


.025 


.031 


.073 


.130 


.051 


.028 


.035 


.086 


.154 


.060 


.030 


.040 


.099 


.178 


.069 


.032 


.044 


.112 


.202 


.078 


.034 


.049 


.125 


.226 


.087 


.037 


.053 


.138 


.250 


.097 


.039 


.058 


.151 


.274 


.106 


.041 


.063 


.164 


.298 


.115 


.043 


.067 


.177 


.322 


.124 


.046 


.072 


.190 


.346 


.133 


.048 


.076 


.216 


.394 


.151 


.052 


.085 


.242 


.443 


.169 


.057 


.094 


.268 


.491 


.188 


.061 


.104 


.294 


.539 


.206 


.066 


.113 


.320 


.587 


.224 


.070 


.122 


.346 


.635 


.242 


.075 


.131 


.372 


.683 


.260 


.079 


.140 


.398 


.731 


.279 


.084 


.149 


.424 


.779 


.297 


.088 


.158 


.450 


.827 


.315 


.093 


.167 



Fig. 676d. 



Digitized by 



Google 



SCREW AND PIN DATA 



159 



FiQ. 676«. 
Screws. 



Flat Fillister Head 
A.S.M.E. Standard 



A = Diam. of Body 
B - 1 .64A - .009 = Diam. of Head 
C-0.66A -.002 -Height of Head 
D =0.173A + .015 - Width of Slot 
Eo.JC» Depth of Slot 



! ih i 



A 


B 


C 


D 


E 


.060 


.0894 


.0376 


.025 


.019 


.073 


.1107 


.0461 


.028 


.023 


.086 


.132 


.0548 


.030 


.027 


.099 


.153 


.0633 


.032 


.032 


.112 


.1747 


.0719 


.034 


.036 


.125 


.196 


.0805 


.037 


.040 


.138 


.217 


.0890 


.039 


.044 


.151 


.2386 


.0976 


.041 


.049 


.164 


.2599 


.1062 


.043 


.053 


.177 


.2813 


.1148 


.046 


.057 


.190 


.3026 


.12^4 


.048 


.062 


.216 


.3452 


.1405 


.052 


.070 


.242 


.3879 


.1577 


.057 


.079 


.268 


.4305 


.1748 


.061 


.087 


.294 


.4731 


.1920 


.066 


.096 


.320 


.5158 


.2092 


.070 


.104 


.346 


.5584 


.2263 


.075 


.113 


.372 


.601 


.2435 


.079 


.122 


.398 


.6437 


.2606 


.084 


.130 


.424 


.6863 


.2778 


.088 


.139 


.450 


.729 


.0295 


.093 


.147 



Fig. 676c. 



Digitized by 



Google 



160 



ENGINEERING AND SHOP PRACTICE 



-- *4>!*— 



Fig. 676/. Oval Fillister Head Screws. 
A.S.M.E. Standard 

A «= Diameter of Body 

B = 1 .64A - .009 = Diam. of Head and Rad. for Oval 

C = 0.66A - .002 = Height of Side 

D = .173A-f- .015 = Width of Slot 

E = iF « Depth of Slot 

F = .134B+ C - Hei^t of Head 




A 


B 


C 


D 


E 


F 


.060 


.0894 


.0376 


.025 


.025 


.0496 


.073 


.1107 


.0461 


.028 


.030 


.0609 


.086 


.132 


.0548 


.030 


.036 


.0725 


.099 


.153 


.0633 


.032 


.042 


.0838 


.112 


.1747 


.0719 


.034 


.048 


.0953 


.125 


.196 


.0805 


.037 


.053 


.1068 


.138 


.217 


.089 


.039 


.059 


.1180 


.151 


.2386 


.0976 


.041 


.065 


.1296 


.164 


.2599 


.1062 


.043 


.071 


.1410 


.177 


.2813 


.1148 


.046 


.076 


.1524 


.190 


.3026 


.1234 


.048 


.082 


.1639 


.216 


.3452 


.1405 


.052 


.093 


.1868 


.242 


.3879 


.1577 


.057 


.105 


.2097 


.268 


.4305 


.1748 


.061 


.116 


.2325 


.294 


.4731 


.192 


.066 


.128 


.2554 


.320 


.5158 


.2092 


.070 


.140 


.2783 


.346 


.5584 


.2263 


.075 


.150 


.3011 


.372 


.601 


.2435 


.079 


.162 


.3240 


.398 


.6437 


.2606 


.084 


.173 


.3469 


.424 


.6863 


.2778 


.088 


.185 


.3698 


.450 


.729 


.295 


.093 


.196 


.3927 



FiQ. 676/. 



Digitized by 



Google 



CHAPTER VII 

BENCH AND VISE WORK 

Preliminary Process — Laying Out 

711. Laying Out Rectilinear Work. Laying out work may 
be described as the operation of placing on a casting, forging or 
partially finished surface such lines as will indicate the location 
and character of the various operations specified by the drawings. 
The necessity of laying out all work is apparent when one realizes 
the amount of time and annoyance that may be saved by it 
in the detection of errors already inherent in the piece or those 
due to previous operations. 

Laying out consists in designating centers by center punch 
marks, drawing lines with a surface gage, scriber and dividers on 
previously coated surfaces, and in tracing irregular forms on 
them from templets. Permanence is given to many lines and 
arcs by dotting and chiseling them. In general, laying out 
should be done on some solid plane surface such as that of a 
bench block or a plate. The surface coating on which the lines 
are described may be chalk, powdered chalk and alcohol, copper 
sulphate — where the surface is free from oil — and any of the 
various coating paints on the market. 

712. Laying Out Cylindrical Work. Cylindrical work is 
usually placed in V blocks or V chucks while flat pieces are placed 
directly on the plate. Centers for cored holes or openings are 
located by fitting a strip of wood across them and driving into 
this piece of wood at the approximate center a tin tag, made by 
bending down the corners of a triangular piece of tin, and upon 
this tag describing the lines and marks which locate the center. 

The operation of locating centers on work is one of importance 
and requires careful attention. Various methods are used, the 
method depending upon the shape of the piece. Cylindrical 
pieces, or those whose cross-section is symmetrical, are usually 

161 



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162 ENGINEERING AND SHOP PRACTICE 

centered by one of the following similar methods: centering by 
dividers, centering by surface gage or centering by hermaphrodite 
calipers. On the ends of the piece, with a distance somewhat 
greater or less than half its diameter, four lines or arcs, enclosing 
a small four-sided figure, are draw^n from points on the perimeter. 
At the center of this figure make the center punch mark, and 
placing the piece, if possible, between the lathe centers revolve 
by hand to determine the accuracy of the work; an error of ^'^ 
or more is too great and should be corrected. Dividers may be 
used for testing the larger pieces. Center punch marks may be 
crowded over by the slanting of the punch before striking. Cup 
centers and center squares are often used for centering where 
square-ended stock is to be had, and centering machines where 
great numbers of similar pieces are to be centered. 

713. Laying Out Drill Work. Chalk the surface to be drilled 
and determine the position of the hole, locating the exact center 
by means of a light center punch mark. About this center 
describe, with the dividers, a circle whose diameter is equal to 
that of the hole desired. On the circumference of this circle 
make eight or more light center punch marks at equal intervals. 
The center punch mark must not be enlarged as it is practically 
impossible to start the drill in the center of the hole without a 
good center mark. 

In laying off subdivisions of a circle, it is considered good 
practice to first subdivide the circumference, if possible, into 
four or six parts and then subdivide these latter divisions; by 
this means any error that may arise from an incorrect setting of 
the dividers, where the ordinary method used, is reduced J to t^, 
according as the piece is divided into four or six parts. 

Hammering and Sawing 

721. Hammering and Peening. Hammers like many another 
machine-shop tool are used wherever possible; however, they are 
designed for pounding. Ordinarily they vary in weight from 
i to 2 pounds and are designated as ball-peen, straight-peen and 
cross-peen, as the shape of the peen varies. The most common 
of these is the ball-peen hammer, weighing from 1 to If pounds. 
This hammer is used for all ordinary work; it being especially 
adapted to riveting and peening, owing to the fact that the 



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BENCH AND VISE WOJIK 163 

effect of the blow by the ball is distributed equally in all direc- 
tions. When a straight or cross-peen hammer is used for this 
purpose, the effect of the blow is greater in one direction than in 
the other. The smaller sized hammers are used on light work 
such as center marking and in die finishing. In using the hammer 
the handle should be grasped at its thickest portion and never 
close up to the hammer. Copper, lead and raw-hide hammers 
are used for striking light blows on finished work where ordinary 
hammers would dent the surface. 

Peening is the process of stretching iron by striking it with 
the peen of a hammer. Crooked or sprung castings may often 
be straightened by judicious peening, and tight nuts and collars 
may be removed by peening, especially when kerosene is poured 
into the joint to loosen the nut. 

7^2. Hack Sawing. Hack saws are used for a variety of 
purposes in the machine shop, mainly where any rough cutting 
operation is to be performed; nevertheless, considerable care must 
be exercised in their use, for the highly tempered blades arc^ easily 
broken in unskilled hands. In tightening the saw in the frame, 
enough tension is given to prevent lateral motion; however, the 
saw should not be unduly strained. The frame should be lifted 
slightly on the backward stroke as this stroke is more destructive 
to the teeth than the forward one. A saw that cramps or sticks 
should be lifted clear of the kerf before trying again, and never 
forced. Owing to their hardness hack-saw blades cannot be 
filed, but they are cheap enough to throw away when dulled. 
Power hack-saw blades are usually heavier, thicker and longer 
than those used in the hand frames. The proper adjustment of 
the feed of the power saw is all that requires especial attention 
in power sawing. Oil is frequently used advantageously in this 
operation on the tougher metals, though this is not general 
practice. 

Threading and Tapping 

731. Threading. When it is necessary to put a thread or 
screw on a piece of stock by hand, dies or screw plates are used. 
These dies are fastened in holders called stocks which, while 
holding the die, afford handles for turning it. The operation of 
cutting the thread is a simple one, though care should be taken 



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164 ENGINEERING AND SHOP PRACTICE 

to eliminate any error that would be caused in work by starting 
the die on crooked. The face of the die should always be perpen- 
dicular to the axis of the piece while it is being threaded. Lard 
oil should be used freely during the operation on wrought iron 
and steel, and care taken to back off the die after each turn a 
distance equal to or greater than each forward cut. 

732. Tapping. When it is desired to cut an internal thread 
or screw by hand a tap is used and the operation called tapping. 
A tap, as we have learned, is a hardened steel screw fluted longi- 
tudinally to form cutting edges and having at the end of its shank 
a squared portion over which fits the tap wrench by which it is 
turned. The common forms of machinist's hand taps are the taper, 
the plug and the bottoming. The reader is advised to refer both 
to the text and to the illustrations in Chapter 6,*' Screw and Pin 
Data," for additional information relative to taps and dies. 

Where it is desired to thread a hole that does not run through 
the piece, a taper tap is used to start the thread and a plug tap 
to complete it to near the bottom. If a full thread is desired all 
the way to the bottom of the hole, a bottoming tap is used. 
Where the holes pass through the material the taper tap alone is 
used. The same precautions should be used with the tap that 
were necessary with the die. Care should be taken to start the 
tap so that its axis coincides with the axis of the hole and to 
back off the tap after each forward turn, as was the case with the 
die in ordinary work; after one or two turns the tap should be 
tested for truth with the try square. 

733. Aligning the Tap. As it is of great importance that a 
tap be started properly, i.e., so that the axis of the tap coincides 
with the axis of the hole — the following effective method of 
securing the alignment is submitted for the benefit of those whose 
experience is limited: Place the work on the table of the drill, 
place the cutting end of the tap drill in the drill chuck and bring 
the work into line by inserting the drill in the hole. Bolt in 
position, insert the tap in the hole for tapping and hold the butt 
end of the drill, which is pointed, firmly in the center of the tap 
while it is being turned, with the tap wrench. This method is 
suggestive of many ways in which the drill and lathe may be used 
for securing the alignment for the rapid and profitable tapping 
of small holes. With this method the tap should always be turned 
by hand. 



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BENCH AND VISE WORK 165 

Lard oil should be freely used during the operation on wrought 
iron and steel; cast iron and brass are tapped dry. 

734. Depth of Tapped Holes. In ordinary practice, holes to 
be tapped in cast iron are drilled to a depth of twice the diameter 
of the screw {2D) and tapped to a depth of 1}Z), while the screw 
itself is made to enter the tapped hole l^D. For wrought iron 
and machinery steel the proportions are the following: Depth 
drilled = IJD, depth tapped = IJD, depth screw enters = ID. 

Chipping 

741. Chipping and Its Applications. Before the advent of 
modem machine tools, nearly all finished metal surfaces had first 
to be chipped and then smoothed up with a file, much after the 
fashion in which we now remove irregularities on castings. Chip- 
ping is still used in places diflicult to get at with a machine, in 
structural work, and when, in the erection of bridges, large 
machines, etc., some unforeseen obstacle must be overcome. The 
chipping of keyways in shafting and pulleys is of common occur- 
rence where the work must be done at night or when repairs or 
additions are to be made where the machinery is already in place. 
A saving of much time and money is often effected by chipping 
under such conditions. 

742. Pneumatic ELammers. Pneumatic hammers for chip- 







61 « 



»M 5« u 




mp. 



Fig. 742. — Section and Parts of a Boyer Pneumatic Hammer. 



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166 ENGINEERING AND SHOP PRACTICE 

ping and riveting have about superseded the old hand method, 
especially in shops where compressed air is to be had. A sectional 
drawing of the Boyer pneumatic hammer together with some 
of the details is shown in the illustration, Fig. 742. 

743. The Chisel. In the cold chisel we meet another modi- 
fication of the wedge in its application to such familiar tools as 
the plane, the knife or the chisel. Presenting the edge of an 
ordinary pocket knife at various angles to a lead pencil will 
produce all the characteristic chips of the drawknife, the wood 
chisel, the plane and the cold chisel. 

For ordinary work the angle between the cutting faces of 
cold chisels and cape chisels should be about 60° and the edge 
ground slightly convex. Harden the cutting end of the chisel 
by a sudden quenching in brine after it has been heated to a 
low, cherry-red. Brighten both faces and draw the temper to a 
straw or brown color. On account of the varying quality of 
steel, and the various methods of hardening, the best temper can 
be obtained only by trial. An edge too brittle, one that crumbles 
or splits, should be re-ground and the temper drawn to a darker 
color. An edge too soft, one that turns over or upsets, must be 
re-ground, re-hardened and the temper drawn to a lighter color. 
Use plenty of water when grinding tools and do not bear too 
hard on the stone; overheating may thus be avoided. Over- 
heating is indicated by a change in color, and should this occur 
it will be necessary to re-temper the tool. 

744. The Work. When possible, place the work to be chipped 
on a flat surface and mark off all horizontal lines with a surface 
gage. Rough surfaces should first be chalked so that the scriber 
may produce well-defined lines. A solution of copper sulphate, 
applied with a brush to a clean iron surface, will deposit a thin 
coat of metallic copper on which any lines that may be drawn 
are readily seen. After drawing the horizontal lines, vertical 
lines may be drawn with the scriber guided by the try-square 
blade, the beam of which rests on the flat surface. Measure all 
lines thus drawn to make sure that no error exists. 

745. The Cut. In clamping work in the vise, copper jaws 
should be used to protect the finished surfaces. In commencing 
the cut the chisel is grasped in the left hand with the thumb 
and index finger close up to the head. In order to lessen the 
liability to injury, the thumb and index finger should be relaxed, 



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BENCH AND VISE WORK 



167 



the second and third fingers should grip the chisel tightly, while 
the little finger is free to guide the chisel as desired. In grasp- 
ing the hammer the little and index fingers should be rather slack, 
while as before the second and third fingers grasp firmly; it will 
be found that a hammer so held may be swung more steadily and 
with greater freedom than when held otherwise. In starting the 
cut care should be taken to hold the chisel at such an angle that 
when the blow is struck the cutting edge will not glance below the 
line and ruin the piece. Hold the cutting edge firmly against 
the work, at the proper angle, and strike light rapid blows until 
the cut is fairly started, when a slow heavy stroke will prove the 
more effective. On account of the brittleness of cast iron it is 
necessary to commence cuts from each end which meet at some 
intermediate point, thus avoiding the danger of breaking off the 
comers. The object striven for is a smooth, even surface; from 
time to time this should be tested with a straight-edge in various 
positions to locate the high places. In chipping wrought iron or 
steel it will be found advantageous to coat the cutting edge of the 
chisel with oil. For a finishing cut, which should be light, the 
chisel may be ground more acutely and the edge whetted on a 
slip stone. 




Fig. 745. — Method of Chipping. 



The method of chipping a surface over 2 inches wide is shown 
in figure 745. The piece, if possible, is clamped in the vise with 
the scribed lines projecting above the jaws. A chamfer is cut 
along the edges with the flat chisel down nearly to the line, and 
may be straightened with a bastard file. With the cape chisel 
diagonal grooves are now run across the surface as indicated, 
their truth being tested with a straight-edge. Care must be 
taken not to cut below the general surface. The strips of remain- 
ing metal, which are about the width of the flat chisel, may be 
removed with it; these cuts while still requiring care are guided 



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168 ENGINEERING AND SHOP PRACTICE 

by the fairly accurate grooves and may be heavier in proportion. 
The constant trying of the chipped portion as the work progresses 
is the only way to insure accuracy. 

746. Chipping Grooves. In working out grooves or keyways 
with a cape chisel care should be taken to keep as close to the 
lines as possible, a light cut being made from end to end. This 
cut will serve as a guide for the others, which may be any desired 
depth. In working out a wude groove a cut should be taken on 
each side close to the lines; the stock between these channels 
may then be removed with heavy cuts. 

Filing and Files 

751. Application and Practice. In fitting and finishing ma- 
chine parts it is often necessary to eliminate the furrows and 
ridges which compose the surface left by the chisel, planer and 
shaper; filing is then resorted to. Files are also used whenever 
a minute reduction in size is desired, for by their careful and 
skilful use great accuracy may be obtained. In order to render 
a rough surface smooth, files of varying degrees of fineness are 
used; the coarse file is foUow^ed by the finer one and the work 
finished in turn by the finest. 

752. The Tools. A file is a piece of hardened steel of the 
desired shape and size, the surface of which is cut into by a series 
of grooves which form sharp points or edges called teeth. These 
teeth are of uniform height and are so arranged that, while each 
one cuts a furrow of its own, those that follow serve to level the 
ridges thus formed, lea\'ing practically a smooth surface. The 
teeth formed by the grooves act on the surface as a series of 
small chisels, each removing a small chip. 

The only other tools necessary for the filing are the iile cardj which 
is essentially a wire and a bristle brush on the same handle, used for 
the purpose of brushing particles from the teeth of the file; a small 
copper chisel for pushing such ''pins" from between the teeth as 
cannot be removed by the use of the card; and a piece of chalk. 

753- Care of Files. A dull file cannot be sharpened and in 
this respect it is unlike other tools; considerable care should 
therefore be exercised to keep it sharp and in good condition. 
Files should never be abused by laying them on top of each other 
or against other tools. When in use the file is liable to "pin," 
i.e., small particles of stock stick between the teeth and scratch. 



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BENCH AND VISE WORK 169 

the work; especially is this so in the case of wrought iron and 
steel. To obtain the best results, it is necessary to clean the 
file at short intervals, not only during its use but before it is put 
away. The cleaning is effected by the use of the file card or 
cleaner and in some cases by means of a piece of copper. 

754. Cross Filing. In moving a file endwise across the work 
commonly called cross filing, the point of the file is held between 
the thumb and the first finger of the left hand, while the handle 
is held by resting the thumb of the right hand upon it and letting 
the end stand against the palm of the hand, the fingers gripping 
it lightly. In moving the file forward over the surface consid- 
erable downward pressure must be applied to cause it to "bite." 
All pressure should be removed in the return stroke and in many 
cases it will be found advantageous to lift the file entirely clear 
of the work. In cross-filing there is a tendency for the hands to 
swing in arcs of circles about the joints of the arms while the 
body swings more or less, depending on the work. To overcome 
these tendencies great care should be taken to move the file in a 
plane parallel to the surface, as any rocking motion will result 
in a rounding of the edges. Owing to the convexity of a file, 
comparatively few of its teeth are cutting at any one time; thus 
it will be seen that short strokes may render the surface of the 
work concave, while with the long ones it may be either flat or 
convex. It will be noticed in filing that small grooves are left 
on the work at each stroke, and that when the strokes are all 
made in the same direction these grooves become deeper, necessi- 
tating their removal by means of a finer grade of file. 

755. Diagonal Filing. By changing the angle of the direction 
of the stroke with the work at short intervals, the grooving 
mentioned above may be avoided. This enables the file to take 
a better cut, since the grooves, running at an angle to the cut, 
cause the file to "bite" more freely and the particles to be more 
easily separated. This also enables the workman to see just where 
the file is cutting and to gage the stroke so that the desired part 
of the surface will be removed. This method is called diagonal 
filing. 

756. Draw Filing. When filing is done by moving the file 
sidewise across the work it is called draw filing and is very gen- 
erally used in finishing turned work where it is desired to remove 
the circular tool marks and to lay them endwise. In draw 



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170 



ENGINEERING AND SHOP PRACTICE 



filing the file is grasped with both hands, one at either end, and 
drawn sidewise toward the operator. Care should be taken to 
hold the file so that the teeth will cut as it moves away from the 
work and to relieve the pressure on the return stroke as in cross 
filing. In draw filing the cut is not as deep as in cross filing, 
the teeth standing at such an angle to the direction of the motion 
that a light shearing rather than a cutting effect is produced; 
very smooth work may be done by this method. A second cut 
or smooth file is best suited for draw filing. 

757. Files and Their Characteristics. A file, as we have 
learned, is a piece of hardened steel of the desired shape and 
size, the surface of which is cut into by a series of grooves which 
form sharp points or edges called teeth. 

The kind of a file, as will be seen from the table, usually refers to its 
cross-section and shape, such as flat, mill, hand, square, round, etc. 

The ct*^ of a file designates the character of its teeth. It is 
single cut when the teeth are cut in one direction only, double 
cut when the teeth are cut in two directions, rasp when the teeth 
are pointed and have no connection with each other. 

Coarseness refers to the size of the teeth as designated by the 
terms coarse, bastard, second cut and smooth; these may refer 
to any and all of the kinds and cuts mentioned. A safe edge file 
has one of its edges smooth and may be any kind or cut. The flat 
or hand file, double cut, is commonly used to produce flat surfaces. 
The mill file, single cut, is used for lathe work. In reference to 
coarseness, the bastard is best adapted for rough work; the second 
cut, while not cutting as rapidly, produces a smoother surface; 
finished surfaces are produced by means of the smooth file. 

758. File Table, Shapes, Cuts, Uses, etc. 

Hand File 



Safe Edge 



Point 




Fig. 758a. — File Nomenclature. 



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BENCH AND VISE WORK 
Table of Files 



171 



Kind or 

Name of 

File 


Section and Shape 


Ordinary 
Cuts 


Ordinary 
Coarseness 


Use in Machine Shop 


Flat. 


Quadrangular. 
Taper Width. 
R'ding Lg'thwise. 
Taper Thickness. 


Double 
Cut. 


Bastard and 
Second Cut. 


Quite common; not con- 
fined to any specific 
kind of work, and em- 
ployed for a great va- 
riety of purposes. 


Mill. 


Quadrangular. 
Taper Width. 
Taper Thickness. 
A Thin File. 


Single 
Cut. 


Bastard. 


Draw filing, for lathe 
work, and to some ex- 
tent for finishing brass 
and bronze. 


Hand. 


Quadrangular. 
Parallel as to Width. 
Taper Thickness. 


Double 
Cut. 


Bastard. 

Second Cut. 

Smooth. 


For finishing flat sur- 
faces; owing to its 
shape and its having 
one safe edge, it is par- 
ticularly useful where 
a flat file would not 
answ^er. 


Square. 


Square. 

Tapers both ways. 


Double 
Cut. 


Bastard. 


Key-ways, rough work, 
and principally for en- 
larging apertures of a 
rectangular shape. 


Round. 


Circular. 
Taper. 


Single 

Cut. 

Spiral. 


Bastard. 


For enlarging round 
.holes, and shaping tho 
fillets on internal an- 
gles. 


Half 
Round. 


Segment. 
Taper. 


Double 
Cut. 


Bastard and 
Second Cut. 


For a variety of uses on 
account of its shape; 
quite common. 


Three 
Square. 


Triangular. 
Taper. 


Double 
Cut. 


Bastard. 


For filing acute internal 
angles, clearing out 
square comers, filing 
up taps, etc. 



Fia. 7586. 



Scraping 



761. Scraping a Plane Surface. After reading what has been 
said relative to scrapers in Chapter 4, Section 433, the reader 
is ready to commence the operation of scraping a surface. 



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172 ENGINEERING AND SHOP PRACTriCE 

Placing the piece, previously trued by planing and filing, at a 
convenient height for the work — it should not be clamped, for 
clamping is liable to spring the piece — it is brushed to remove 
any dust or dirt that may be on the surface. Any burrs, fuzz or 
irregularities are removed by the use of smooth or dead smooth 
files. The surface plate is now applied; before applying, however, 
its face is wiped and coated with the marking material. A 
marking material may consist of any red or black mixture that 
is not gritty; a mixture of lard oil and Venetian red makes an 
excellent marking substance. A surface plate is applied face 
downward on the work and rubbed back and forth over the 
entire surface; no pressure is necessary as the weight of the plate 
is sufficient. Upon the removal of the plate irregular patches of 
marking material will be found, which indicate the high spots on 
the surface; a few strokes of the scraper will remove them. 




Fig. 761. — Scraping a Surface Plate. 

The handle of the scraper is held in the right hand with 
the thumb extended along the top, as was the case in grasping 
the file. The blade is grasped with the left hand, as close to the 
cutting edge as is convenient. The scraper is usually, though 
not always, held at an angle of 30° with the work, and only 
that amount of pressure necessary to remove the required metal 
is applied. The scraping is effected by pushing the scraper away 
from the operator. The cuts are square and vary from y to {" 



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BENCH AND VISE WORK 173 

on a side and are i^ to J* apart. They are taken at right angles 
to each other in such a manner as to give to the surface a checker- 
board effect. After the surface is scraped both ways in the 
manner indicated, the workman should wipe his hands free of grit 
and rub it over the entire face of the surface to smooth the 
marking; the plate is then applied to the work as before, and the 
operation repeated. The truer the surface becomes, the thinner 
should be the coating of marking material on the plate. 

Turpentine is often used advantageously, for, in addition to 
lubricating the surfaces, it also facilitates the work of scraping. 

762. Scraping in the Lathe. Scraping in the lathe is a vastly 
different process from scraping by hand and is resorted to as a 
substitute for filing. The shank of a lathe tool clamped in a 
tool post may be used as an improvised support for the scraper. 
In work of this character it is necessary to take light cuts, to 
hold the scraper firmly and to work from the center out. Chat- 
tering may sometimes be prevented by placing a piece of leather 
imdemeath the tool. 

Keys, Keyfitting and Broaching 

771. Key Nomenclature. The machinist uses the term key 
to designate that piece of steel, imbedded in the shaft and filling 
a groove in the hub, that holds the parts in their relative positions. 

A key-seat is the groove in the shaft while the key-way is the 
groove in the hub. Ordinarily keys and key-ways are made to 
taper, usually Y per foot. A straight key is often termed a 
feather. Woodruff patent keys are made by slitting a disc of 
cold rolled bar across its diameter and imbedding it in a key-seat, 
made by sinking into the shaft, to the proper depth, a milling 
cutter, whose diameter is equal to that of the bar. Some provi- 
sion is generally made for removing keys; either the key-seat is 
longer than is necessary so that the key may be driven out, or 
the larger end of the key is provided with a head; in this latter 
case the key is removed by the use of a pinch bar or wedge. 

772. Keyfitting. Ordinary keys are usually machined a 
trifle larger than the key-seat and then fitted, by filing, to size. 
The first step in fitting is to determine whether the sides of the 
key-seat and key- way have been cut straight; any inaccuracy 
should be rectified by enlarging just enough to straighten them. 
The comers of the key are very slightly rounded and both the 



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174 ENGINEERING AND SHOP PRACTICE 

key-seat and key- way are coated with some marking material; 
the key is then lightly driven into position, when it is withdrawn 
and filed where a bearing is indicated; this process is repeated 
until a tight driving fit on all sides is secured. A well-fitted key 
is bedded firmly against the top and bottom and it is absolutely 
essential that it have a driving fit on the sides, as it is entirely 
the side fit that is depended upon to hold the shaft and the hub 
together. The pressure on the top and bottom of the key should 
be merely sufficient to draw the opposite side of the bore of the 
hub firmly to the shaft. There is practically no tendency to 
break the hub or throw the work out of line by making the key 
fit tight on the sides if the sides be straight; however, it is a 
very easy matter to crack a hub or to throw it out of line 
by overstraining at the top and bottom of the key. In fitting, 
care must be taken to coat the key with the marking material 
which also acts as a lubricant; if driven in dry, the key will 
surely cut. 

773. Key-way Cutting. Small key-ways may sometimes be 
advantageously cut by hand in the lathe in the following manner: 
A special tool, somewhat similar in shape to a boring tool and 
ground like a slotting tool at the end, is clamped in the tool 
post and brought up to the bore to be key-wayed; the tool with 
the carriage is then traversed back and forth through the 
hub by hand, taking light, planing chips until the work is 
finished. 

Key-ways and key-seats are made in many ways; they are 
sometimes chipped and filed; more often, however, the milling 
machine, planer or shaper is used, while in the larger shops 
specially designed machines called key-seaters are employed. 



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BENCH AND VISE WORK 



175 



774. Table of Standard Key-seats. 

. Keys and Key-ways Taper I*' per Foot 



Diameter 

Shaft 

In. 


Width 
In. 


Depth 
In. 


Diameter 

Shalt 

In. 


Width 
In. 


Depth 
In. 


Diameter 

Shaft 

In. 


Width 
In. 


Depth 
In. 


1 


i 


A 


6 


11 


i 


9 


1| 


A 


U 


A 


A 


51 


11 


i 


91 


1| 


A 


U 


A 


A 


51 


11 


i 


91 


1| 


A 


1| 


i 


1 


51 


11 


A 


91 


2 




li 


1 


1 


51 


H 


A 


91 


2 




1| 


A 


1 


51 


11 


A 


9} 


2 




1| 


A 


1 


5i 


11 


A 


»f 


2 




li 


i 


A 


51 


11 


A 


91 


2 




2 


} 


A 


6 


11 


A 


10 


2 




2i 


i 


A 


61 


11 


A 


101 


2 




21 


i 


A 


61 


11 


A 


101 


2 




2| 


1 


i 


6i 


11 




101 


21 




21 


i 


1 


61 


11 




101 


21 




2| 


! 


i 


6J 


11 




101 


21 




21 


! 


i 


6| 


U 




10} 


21 




21 


f 


i 


61 


11 




101 


21 




3 


i 


i 


7 


u 




11 


21 




31 


i 


1 


71 


11 




111 


21 




3i 


1 


i 


71 


11 




111 


21 




3| 


i 


A 


71 


ll 




111 


21 




3i 


i 


A 


71 


11 




111 


21 




3| 


} 


A 


71 


ll 




111 


21 




3| 


i 


ft 


7} 


11 




111 


21 




3i 


1 


A 


7i 


11 




Hi 


21 




4 


1 


A 


8 


11 




12 


21 




4| 


1 


A 


81 


ll 




121 


21 




4i 


1 


A 


8J 


If 




121 


21 




4| 


1 


A 


8i 


U 


A 


121 


21 




4i 


1 


A 


81 


n 


A 


121 


21 




41 


11 


i 


8} 


ij 


A 


121 


21 




41 


n 


i 


8} 


ij 


A 


12} 


21 




4i 


11 


i 


81 


li 


A 


121 


21 





Fig. 774. 

775. Broaching or Drifting. Broaching or drifting may be 
defined as the process of forming holes in metal by driving or 
forcing a cutter of the desired form through previously drilled 
holes. In broaching, the greater amount of stock is always 



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176 ENGINEERING AND SHOP PRACTICE 

removed by drills, if need be, of var)dng sizes. The square hole 
in socket or chuck-screw wrenches is generally made with a 
broach. Key-ways are often cut by the following process of 
broaching: A broach, whose width is that of the key-way, having 
a cutting edge and guide lip as shown in the illustration. Fig. 775, 

Guide Flog 




1=] 



Broach 



\ 



Xiaer 
Fia. 775. — Tools for Broaching Key-wajrs. 

is made; a guide plug is then turned to fit the bore of the hub, and 
a tapering groove of proper depth cut in it; the drift or broach 
is then driven through the guide groove while its cutting edge 
removes a chip. In order to obtain the desired depth, liners or 
shims, cut from sheet metal, are placed in the bottom of the 
guide groove until a sufficient number of cuts, to secure the 
proper depth, are made. 

Fits and Fitting 

781. Investigation. For an exhaustive investigation of fits 
and fitting, the student is referred to a paper by the author, and 
its discussion, forming part of Volume 24 of the Transactions of 
the American Society of Mechanical Engineers. What follows is 
in a measure an abstract of the author's paper; however, the 
formulas relative to forcing and running fits and to limits for 
limit gages, have been changed in the direction indicated by the 
bulk of the criticisms. All the formulas will now be found to 
indicate, in the main, the best practice in this direction. 

782. Fitting Processes. Before the advent of modern meth- 
ods of manufacture, the majority of the fitting was done by hand 
and was dependent, for its accuracy, upon the skill and judgment 
of the workman. An experienced workman with a well-educated 
eye and sense of touch was able to make fits within a limit of a 



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BENCH AND VISE WORK 177 

few thousandths of an inch, by the old cut and try method. 
These methods have been superseded and the use of limit gages 
renders such skill and experience unnecessary. The operation of 
fitting a plug to a bore was accomplished by a delicate calipering 
of the bore with inside calipers, transferring this dimension to 
outside calipers and turning or filing the piece to this dimension. 
Such uncertain methods as interposing between the legs of the 
calipers a film of saliva or paper, to secure the fit allowance, were 
used. The limit thus secured was dependent entirely upon the 
skill of the workman with the calipers and his judgment regarding 
the allowance for the fit in hand. Such methods have been 
superseded and with them the uncertainty and expense of the 
cut-and-try methods. These, together with much of the skill, 
have given place to the more rational and cheaper operations of 
fitting and interchangeability which sprang into use with the 
advent of limit gages. 

When the fit is to be made by hand and the work to be filed 
to fit a certain gage, or when a certain accuracy is desired, it is 
the practice, empirically speaking, to leave small lathe work, 
after the finishing cut, about .002'' large and to remove this stock 
with what is termed a *' float," usually a single cut, bastard or 
second cut, mill file. The end next the dead center should be 
filed first so that the gage will just enter, and the operation of 
finishing gradually carried toward the live center, leaving the 
surface such that when the gage or caliper is passed over it, no 
perceptible looseness is detected. 

Grinding, scraping, milling and filing may be termed fitting 
operations, and for more explicit information regarding these 
subjects the reader is referred to the chapters dealing especially 
with them. 

783. Forcing Fits. Forcing fits may be defined as those 
machinery fits which require the use of some form of press, gen- 
erally hydrostatic, to complete the assembling operation. This 
sort of fit finds its most general application in the fitting of car 
wheels and axles, in the assembling of cranks and crank pins, 
cranks and crank shafts and crank shafts and armatures. 

Regarding the assembling process, or the manipulation of 
forcing fits, we find the following governing conditions: (1) The 
allowance. This should never be so great as to prevent the 
stress from coming well within the elastic limit or crushing strength 



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178 ENGINEERING AND SHOP PRACTICE 

of the materials employed. (2) The surfaces. In general we 
may say regarding the surfaces for this kind of fitting, that the 
best results are obtained when both surfaces are ground to fit 
gages. The conditions, in some instances, render this impracti- 



Note; Curves for the Running Fits will \n* found on the Limits Diagram 

Figs. 783, 785, 786. — Assembling Fit Curves. 

cable; however, the surfaces of the pieces to be assembled should 
be as smooth as it is practical to make them. (3) The lubrica- 
tion. Linseed oil makes an excellent lubricant for assembling 
forcing fits. (4) The alignment. It is important to start the 



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BENCH AND VISE WORK 179 

plug accurately; so important is this that, to secure an accurate 
alignment, some engineers resort to the use of two diameters — 
each half the length of the fit — differing by but a few thousandths 
of an inch. The additional advantage of having to force the plug 
through but half the length of the fit, it is claimed, greatly reduces 
the maximum forcing fit pressure. 

The following formula gives the allowance for forcing fits in 
thousandths of an inch: 

A = II 2) -f .5. where A = allowance or difference in diameter 
between the plug and bore; and D = the nominal diameter of the 
fit. 

784. Forcing Fit Pressures. The following discussion of 
forcing fit pressures is taken bodily from the author's paper on 
*' Fits and Fitting "; the excuse for the technical nature of the sub- 
ject-matter and its presentation here being that, on the one hand, 
the problem of determining forcing fit pressures is by no means 
simple, while, on the other hand, a knowledge of them is of consid- 
erable importance to him who has to do with this class of fits. 

In forcing fit pressures the fixed conditions are generally 
the following: The materials employed; the nominal diameter, the 
length of the fit, and the thickness of the hub. With these 
conditions the pressure necessary to assemble a given forcing fit 
will vary, Mr. Kelley concludes after his experience with about 
eight hundred forcing fits on regular engine work: 

(1) Directly as the area of the surface of the fit for a given 
diameter. 

(2) Directly as the allowance — the difference in diameter 
between the plug and the bore. 

(3) As a function of the radial thickness of the hub. 

(4) As the materials employed and the nature of the machined 
surfaces. 

The investigation for a pressure curve was undertaken on 
this basis — on the assumption that these conclusions are correct. 
After considerable work a simple equation for a representative 
pressure curve was established. This equation gave essentially 
the results obtained by the use of Mr. Kelley 's experimentally 
derived curve, and while possessing the advantage of mathematical 
deduction, it had the additional advantage of conforming to 
experience and becomes, therefore, thoroughly practical in its 
application. 



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180 ENGINEERING AND SHOP PRACTICE 

The curve, (Fig. 784) an hyperbola whose equation is 

Di.oe 
where PF is the pressure factor and D the nominal diameter of 
the fit, assumes the hub to be twice the diameter of the plug, 



Fig. 784. — Forcing Fits. Pressure Factor Curve, 
the materials employed to be machinery steel plugs and cast-iron 



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BENCH AND VISE WORK 181 

hubs, and the machined surfaces to be practically true and free 
from tool marks. Should the hub diameter exceed twice that of 
the plug, the pressure, according to condition three, will be 
somewhat greater — the amount being obtained by the construc- 
tion of another hyperbola. Should the materials employed be 
other than those the curve assumes, the pressure, according to 
condition four, will again vary, necessitating the determination 
of another value of PF. The few values obtained from the 
meager data relative to this particular point seem to indicate 
that a new value of PF might be obtained by multiplying PF 
directly by the ratio existing between the average value of the 
crushing strength of the two new materials and the average 
value of the crushing strength of cast iron and machinery steel. 
Moreover, the investigation disclosed the problem to be far too 
complicated to admit of so simple a solution. The dearth of 
particular values and the incompleteness of the experiments 
leading to the above indication were such as to influence the 
author to say that the statement is of no practical value. How- 
ever, it may be well to state that the problem was first attacked 
on the assumption that a solution might be had from a comparison 
of the moduli of elasticity of the materials. This position was 
rendered untenable: first, because in materials such as cast iron, 
which have no well-defined elastic limit, the modulus decreases 
from a maximum near the beginning of the test; second, as some 
permanent deformation of the bore and plug generally results as 
a consequence of the assembling, the elastic limit of the material 
is obviously passed; this furnished a clew for attacking the prob- 
lem with reference to the crushing strength. Then again the 
investigation proceeded with a treatment of the hub as a thick 
hollow cylinder under tension. Were this assumption correct, 
the formulas of Professors Barlow and Merriman should be appli- 
cable and the tension on every concentric layer, caused by the 
internal pressure, would vary inversely as the square of its dis- 
tance from the center. This position is faulty in that cast iron 
is not homogeneous in texture, is not incompressible, and when 
used for the materials of cylinders of hydraulic presses, the 
thickness which obtain are such that the stresses calculated by 
these formulas would postulate the use of steel to render them 
reasonably safe. This latter may not be a parallel case, as 
hydraulic cylinders are usually solid at one end. 



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182 ENGINEERING AND SHOP PRACTICE 

In passing, the author concludes that the influence which the 
use of different materials will have on the pressure may only be 
satisfactorily determined by experiment. 

The tabulated values of PF from this curve will prove the 
more convenient for ready reference; however, the method of 
using the curve is as follows: select the nominal diameter of the 
fit and follow its ordinate up to the curve; from this intersection 
follow horizontally to the left and read PF the pressure factor. 
The equation for the pressure is 
Pressure in Tons = 

Area of surface of fit X dif . in diam. between plug and bore X PF 

2 

The result will be the pressure in tons required to force the plug 
home. A foreman may thus also easily determine whether or 
not his press is of sufficient capacity for the work in hand. 

785. Shrinking Fits. Shrinking fits are employed for a 
variety of work and are generally used in the smaller shops where 
no suitable press is to be had for assembling the work. 

The allowance for shrinking fits in thousandths of an inch 
may be obtained from the equation 

This equation gives allowances which agree with the standard 
adopted by the American Railway Master Mechanics Association 
for locomotive wheel-center and tire gages. The agreement is 
identical to the thousandth decimal place, this being the extent to 
which their standard is carried. (See Fig. 785, page 178.) The al- 
lowances obtained by the use of this formula, while not excessive, 
are sufficient to insure a tight fit, thus avoiding the danger of 
excessive shrinkage stresses, ofttimes deemed negligible, which 
are always additional to those incident to actual service. Taking 
the modulus of elasticity of steel at 30,000,000 the stress caused 
by this amount of shrinkage would be about 33,000 pounds per 
square inch, which is well within the elastic limit of machinery 
steel. 

Considering this class of fitting with a view to obtaining the 
greatest resistance to tension and torsion, we discover that 
shrinking fits are far superior to forcing fits, they being, under 
like conditions, as Professor Wetmore has shown, uniformly 
about three times as tight both in tension and torsion. Experi- 



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BENCH AND VISE WORK 183 

ments seem to indicate that, in this class of fits, the resistance 
to torsion increases more rapidly with the diameter than does 
the resistance to tension. 

In the manipulation, good practice maintains that a piece 
should rarely be heated hotter than a very dull red heat — about 
800° F. — and under no consideration to the scaling point. 
This temperature, of necessity, limits the fit allowance to some- 
thing less than 700° x .00000556 = .003892 per unit diameter 
for cast iron. It will be found, upon an examination of the 
formula, that the heating to this temperature is ample for the 
allowances given. 

Regarding the process, better results will be obtained if the 
entire piece be heated slowly and uniformly instead of trying to 
hasten matters by "blazing up" through the bore. The latter 
practice is sometimes negative in its results; in cases, perma- 
nently reducing the bore diameter instead of increasing it as 
desired, the expansion being inward instead of outward. In 
general, it may be said that this class of fitting requires more 
skill and experience in its manipulation than does force fitting. 
Not only in the heating and assembling is this skill and experience 
necessary, but in the cooling as well. 

786. Driving Fits. Regarding driving fits, it may be stated 
that this method of assembling is about obsolete. However, a 
field may still exist for such small work as the assembling of the 
smaller pins and cranks of valve gearing, where the allowance 
A given in thousandths of an inch, obtained by the formula, 

il = i D + .5 
might be used to advantage when the fit is made in an arbor 
press or by some kindred method. (See Fig. 786, page 178.) The 
allowances by this formula might also be used for some classes 
of tight-keyed fits; however, the practice of driving home a 
plug by means of blows is too crude to be used except where no 
other method is available. 

As will be inferred, what has been said regarding the condi- 
tions and preparation of the work for forcing fits applies equally 
well to driving fits. It might also be stated that where a driving 
fit must be used, it is essential, when driving the piece home, to 
have the surfaces well lubricated and the piece containing the 
bore firmly supported; a timber, a block, of wood, a copper or 
soft -faced hammer should be used so as not to mar the surface. 



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184 ENGINEERING AND SHOP PRACTICE 

787. Running Fits. A running fit is designed to allow the 
surfaces in contact to move or revolve freely over each other. 
The more nearly the surfaces in contact approach perfection, the 
better will be the fit; however, there should be a sufficient differ- 
ence in diameter to admit of motion and lubrication. The 
difference in diameter to be allowed in any given fit depends upon 
the following conditions: the nature of the machined surfaces, 
the kind of metals in contact, the length of the fit and its diam- 
eter, and the pressure and kind of work. The perfection of the 
fit, depending largely, as it does, upon the surfaces in contact, 
renders it imperative that they be smooth and true. When 
possible, in the smaller sizes^ bored holes should always be reamed, 
as this not only insures a standard size but finishes the hole 
comparatively smooth and true. 

Two formulas are given for running fits; one for close running 
fits, to be used for ordinary work, slow speeds and light pressures, 
and the other for free running fits, to be used for highspeeds, 
heavy pressures, rocker shafts, etc. The formula for the close 
running fits la A = ^\ D + l.O where A = allowance in thou- 
sandths of an inch. These allowances, while seeming unneces- 
sarily small, are such as give a high standard of running fits. 
The formula for free running fits is A = /^D + 1.5. It will be 
remembered, of course, that in order to obtain the shaft diameter, 
the allowance should be subtracted from the diameter of the 
bearing, which is generally finished by a standard reamer. This 
formula assumes the condition of the surfaces in contact to be 
similar to that obtained by the use of a reamer, and the allow- 
ances will be found to fall within the limits given in Section 788 
on limits for limit gages. 

In passing, it might be well to give a few cautionary sentences 
regarding the production of satisfactory running fits. Regarding 
the truth and accuracy of bored holes, practice indicates that the 
best results are obtained with a very light cut, a high speed and 
slow feed. In light chuck work there is a tendency, in tight- 
ening the chuck jaws, to distort the piece, and it may be necessary 
in some instances partially to relieve the pressure for the light 
finishing cut. The most satisfactory results are obtained, in 
fitting, where limit gages are used. Where no limit gages are to 
be had, in many instances it will be found advantageous to 
finish the bore first, as it is easier to fit the shaft to the hole than 



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BENCH AND VISE WORK 185 

vice versa. When a fit is made, any tool marks left on either the 
shaft or the bore wear away rapidly and defeat the purpose of 
the work. Not only is their helical construction conducive to 
rapid wear, but perfect lubrication is rendered almost impossible 
as the grooves tend to lead the oil out of the bearing. It is 
desirable to have the surfaces in contact ground, as they then 
approach perfection; where this is not feasible, they should be 
filed and polished. On good work a very few strokes of the 
file will suflfice to remove the tool marks; little or no filing should 
be attempted after their removal, as the filing of cylindrical 
work is at its best a negative process where truth and accuracy 
are to be sought. 

788. Limits for Limit Gages. Limit gages, as we are well 
aware, are used primarily as time savers; they avoid the waste 
of time in finishing parts unduly accurate, while still having them 
accurate enough to meet all the demands of interchangeable 
manufacture. The selection of the limits of variation for any 
given class of work requires experience and sound judgment. 
As it is clearly a matter of time saving, the problem resolves itself 
into two phases: the accuracy and efficiency of the machine on 
one hand and the rapidity of production on the other. The 
largest limit of variation, then, that will produce the desired 
accuracy and efficiency in the machine is the one to be selected. 
For this reason the selection of limits proves a hazardous under- 
taking for any but the one who has to do with the production of 
the machine; however, the following diagram is submitted as 
being applicable to machine tool, engine work and similar practice. 

In the manufacture of limit gages there are reasons why one 
of the sets should be made one half the allowable variation larger 
than the nominal size, while the other set should be made just as 
much smaller. This, it is believed, is the practice of the best 
manufacturers, though in some of the data investigated, such 
was not the case. The formula for the curve on the diagram is 

— = JZ) 4- .3 and gives half the limit variation in thousandths 

of an inch, plus or minus as desired. 

An explanation of the limits diagram is as follows: The dis- 
tance betewen the lines A and B on any nominal diameter gives 
the maximum variation of the reamer or bore; as for instance, on 
the 2-inch diameter, the maximum variation is .0011 inches. The 



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186 ENGINEERING AND SHOP PRACTICE 

line C is the curve for close running fits (A = ^D + 1.0). It 
will be seen that when the reamer limits are referred to this curve, 
the maximum difference in diameter between the hole and the 
shaft is the distance, on any nominal diameter, between the 



O 

'a 



2 



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BENCH AND VISE WORK 



187 



lines A and C; and that the minimum difference is the distance 
between the lines B and C. For instance, for a 4-inch diameter, 
it will be seen that the maximum difference is .0031*, while the 
minimum difference is .0015/ 

789. Tabulated Data Relative to Fits and Fitting. In order 
to place the results of this investigation in the most convenient 
form, that adequate for ready reference, the allowance values for 
each class of fits were calculated and tabulated under the following 
arrangement : 



Pressure 
Factors 


Nonliwl 

Diam.of 

Fit 


Fordng 

Fit 
Allow, 
ances 


Shrinking Fit 
Allowances 


Driving 
Fit Allow- 
ances 


CIo«e 
Running 
Fit Allow- 
ances 


Free 
Running 
Fit Allow- 
ances 


Umits for 

Limit Gages 

+ or- 




V 






.0006 


.00108 


.00161 


.00033 




V 






.0008 


.00115 


.00172 


.00036 




Y 


1 




.0009 


.00123 


.00183 


.00039 


391 


1 " 


' .0017 


.0016 


.0010 


.0013 


.00194 


.0004 


319 


i ^*' 


.0023 


.0021 


.0013 


.0015 


.0022 


.0005 


240 


V 


.0029 


.0026 


.0015 


.0016 


.0024 


.0006 


156 


3- 


' .0041 


1 .0037 


.0020 


.0019 


.0028 


.0007 


115 


4' 


■ .0053 


.0048 


.0025 


.0023 


.0033 


.0008 


91 


h" 


.0064 


.0058 


.0030 


.0026 


.0037 


.0009 


75 ; 


6" 


.0076 


.0069 


.0035 


.0029 


.0041 


.0011 


64 


r 


.0088 


.0079 


.0040 


.0032 


.0046 


.0012 


55 


%" 


.0100 


.0090 


.0045 


.0035 


.0050 


.0013 


48.5 


^ 


.0112 


.0101 


.0050 


.0038 


.0054 


.0014 


43 


\(f 


.0124 


.0111 


.0055 


.0041 


.0059 


.0016 


39 


XV 


.0136 


.0122 


.0060 


.0044 


.0063 


.0017 


36 


\2r 


.0148 


.0133 


.0065 


.0048 


.0068 


.0018 


30.4 


w 


.0171 


.0154 


.0075 








26.4 


w 


1 .0195 


.0175 


.0085 








23.3 


18-^ 


.0218 


.0196 


.0095 








20.8 


20^^ 


.0243 


.0218 




1 






18.8 


22' 


; .0266 


.0239 










17.2 


24*^ 


' .0290 


.0260 










15.1 


27-^ : 


.0326 


.0292 










13.5 


30-^ : 

38' ; 


.0361 


.0324 
.040 








CO 




44' 


iC 


.047 "^ 


»c 


q 





Q 


II i 

1 


50^ 
56' 
62' 
66' 


1 


.053 ^ 
.060 q 
.066 t- « 
.070 '"1,'" 

^ 
Fig. 


4- 
^ 1 


+ 

-- 2 
II 


+ 
II 


1! 






789. 





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CHAPTER VIII 

TURNING 

Turning Machines 

8ii. Lathes. Lathes are probably used for a greater variety 
of operations than any other machine tool, and to this reason is 
due the variety of classes and the wide range of sizes in each 
class. The typical metal worker's lathe — the most common of 
all — is the engine lathe; the one to which most of our remarks 
will be directed. 



Fig. 811. — Lodge and Shipley Patent Head Lathe. 

In cases where the engine lathe could not be used to advantage, 
special lathes have been designed, among the more common of 
which are the following: 

812. The Tool-maker's Lathe. A tool-maker's lathe is an 
engine lathe manufactured wuth great care, and possessing extra 
attachments that are desirable for tool making. 

188 



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TURNING 



189 



Fig. 812. — Pratt & Whitney Tool-maker's Lathe. 

813. The Gap Lathe. A gap lathe is an engine lathe so de- 
signed that it will swing pulleys and similar large work through 
a gap or depression in the bed near the head-stock. 




Fig. 813. — Gap Lathe. 



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190 



ENGINEERING AND SHOP PRACTICE 



814. The Axle Lathe. An axle lathe is a peculiarly designed 
lathe with two carriages used for finishing car axles; the work is 
generally driven from the center. 

815. The Wheel Lathe. A wheel lathe is an especially de- 
signed lathe for finishing locomotive driving wheels and similar 
works, the work often being driven from the center. 

816. The Turret Lathe. A turret lathe is essentially a manu- 
facturing lathe, the characteristic feature of which is a turret, 
designed to bring in rapid succession a number of varieties of 
tools which act on the stock passed through the spindle and held 
in the chuck. To this class of lathes belong screw machines, 
monitor and brass-worker*s lathes. 

817. The Pulley Lathe. A pulley lathe is a type of specially 
designed lathe for turning pulleys. 




Fig. 817. — Pulley Lathe. 



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TURNING 191 



C8 



3 

"3 



OS 



CO 

s 

6 



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192 ENGINEERING AND SHOP PRACTICE 

817J. The Crank-shaft Lathe. A crank-shaft lathe is a type 
of specially designed lathe for turning multiple-throw crank 
shafts. The drive is generally uniform from end to end and no 
difficulty is experienced in keeping any number of crank pins of 
the same shaft in positive alignment. 



Fig. 817i. — Tindel Albrecht Crank-shaft Machine. 

818. The Bench or Precision Lathe. A bench or precision 
lathe is designed for finishing fine, small work where great accu- 
racy is desired; it resembles closely a watch-maker's lathe and is 
intended for light work only. 



Fig. 818. — Rivet Bench or Precision Lathe. 

819. The Speed or Hand Lathe. A speed or hand lathe is 
similar to a wood-worker's lathe and is designed to rotate the 



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TURNING 193 

work at a higher speed than the ordinary engine lathe; with it such 
hand tools as gravers and files are used. A great deal of finishing, 
drilling and countersinking is done with profit on this machine. 



Fig. 819. — Blount Speed or Hand Lathe. 

The Engine Lathe 

821. Description. An engine lathe is a lathe equipped with 
a lead screw used for cutting screw threads, and power feeds for 
actuating the motion of the tool; it is driven from a counter-shaft 
or by direct connected motor. 

In the following description of a standard type of a screw- 
cutting engine lathe are given briefly the names and functions of 
its various parts. Referring to figure 821a, we have: 
B Bed or Shears carrying the working parts of the lathe. 
W Ways planed on the bed to guide the carriage and tail-stock. 
R Rack for traversing the carriage. 
LS Lead Screw used for traversing the carriage. 
CGA Change Gear Arm. 

FR Feed Rod, which actuates the feed mechanism in the apron. 
ASB Automatic Stop Block. 
RFC Rod Feed Cone. 



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194 ENGINEERING AND SHOP PRACTICE 



2 









L Legs supporting the bed. 

HS Head-Stock carrying driving mechanism. 

Sp. Spindle which, through a dog, face-plate or chuck, transmits 

its motion to the work. 
LC Live Center inserted in the spindle. 
FP P'ace-Plate screwed to the spindle. 
SDC Stepped Driving Cone, of which 1, 2, 3, 4, 5, are the 1st, 

2d, 3d, 4th and 5th steps respectively. 



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TURNING 195 

BG Back Gears used for the slower spindle speeds. 

BGL Back Gear Lever for throwing the back gears in or out of 

action. 
DG Driving Gear keyed to the spindle. 
LBN Latch Block Nut on the side of DGj which fastens the driving 

gear to the cone pulley when driving direct for the faster 

speeds, with the back gears out. 
RL Reverse Lever. 
CGT Change Gear Table. 
St. Stud. 

SCG Stud Change Gear used in screw cutting. 
SFC Stud Feed Cone. 
ICG Intermediate Change Gear. (Idler.) 
LSG Lead Screw Change Gear. 
C Carriage, the upper portion of which (S) is called the 

saddle; the front portion (A), rigidly fastened to the 

saddle, is the apron. 
S Saddle, part of the carriage carrying the slide rest and tool. 
SR Slide Rest (invented by Henry Maudslay in 1794). 
CR Compound Rest. 

TP Tool Post in which the lathe tool is held. 
TTS Threading Tool Stop, used in screw-cutting, for determining 

the depth of cut. 
SRC Slide Rest Crank, for operating the slide rest. 
CRC Compound Rest Crank, for operating the compound rest. 
CCS Carriage Clamping Screw. 

A Apron, part of the carriage; contains the feed mechanism. 
LSL Lead Screw Lever, which clamps the lead screw nut on 

the lead screw. 
CFK Cross Feed Knob, for throwing in the automatic cross feed. 
AFK Automatic Traverse Feed Knob, for throwing in the auto- 
matic traverse feed from the feed rod. 
TPK Traverse Pinion Knob. 
TC Traverse Crank, for moving the carriage back and forth on 

the ways. 
TS Tail-Stock. 
DC Dead Center; most of the lathe work is swung between the 

live and dead centers. 
TSS Tail-Stock Spindle. 
CL Clamp Lever for clamping the tail-stock spindle in position. 



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196 ENGINEERING AND SHOP PRACTICE 

OP Oil Pocket which holds oil for oiling the dead center. 

HW Hand Wheel for adjusting the tail-stock spindle and the 

dead center. 

CN Clamping Nuts, for clamping the tail-stock to the bed. 

SS Set-over Screws, for setting over the tail-stock spindle when 

taper turning. 

CG Change Gears for screw-cutting and geared feeds. 

SLR Steady Rest, used to support long, slender work. 

CS Counter Shaft. 

CL Clutch on counter-shaft. 

H Hangers for counter-shaft. 

PR Pulley Rest. 

FP Face-Plate. 



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TURNING 197 



Fig. 821tta. — Reed Engine Lathe, Motor Driven. 



Fia. 8216. — Bradford Engine Lathe. 



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198 ENGINEERING AND SHOP PRACTICE 



Fig. 821c. — Section through Head-stock. 



Fig. 82ld. — Apron Front. 



Fig. 82 le. — Apron Back. 



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TURNING 199 



Fig. 821/. — Taper-turning Attachment. 

822. Characteristic Operations. It is important to under- 
stand the following operations and adjustments of the lathe before 
starting work: 

1. The method of obtaining, after its determination, the 
proper speed for the specific work in hand. This is accomplished 
by shifting the belt to the proper step of the cone pulley and 
adjusting the back gears in or out as the work demands. 

2. How to instantly reverse the lathe. On most lathes this 



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200 ENGINEERING AND SHOP PRACTICE 

is accomplished by throwing the shipper arm in the opposite 
direction from that which runs the lathe forward. 

3. The method of adjusting the work in the lathe. This 
topic is treated more fully under the heads of Centering, Sec. 831, 
Lathe boring operation, Sec. 932, Adjustment in chucks, Sec. 933, 
Adjustment on face-plate. Sec. 934, and Adjustment on car- 
riage, Sec. 935. 

4. The adjustment of the steady and follow rest. The method 
of adjusting and clamping the steady rest on the ways and the 
follow rest on the carriage. 

5. The various adjustments of the tail-stock, adjusting the 
tail-stock spindle, clamping the tail-stock in the proper position, 
how to remove both live and dead centers, and the method of 
*' setting over" for taper turning. 

6. The method of adjusting the automatic feed mechanism 
after the determination of the desired feed. How this feed 
motion is transmitted by means of feed cones and gears to the 
feed rod and carriage; the location and operation of the feed 
knobs and clutches and how to instantly throw either of the 
feeds into or out of operation. Also the method of reversing the 
direction of the feed. 

7. How the carriage is brought into its proper relation with 
the work by means of the traversing crank; also the method of 
disengaging it from the rack by means of the traverse pinion 
knob, and how to clamp it in position on the ways by means of 
the carriage clamping screw. 

8. The operation of all the other mechanism contained in 
and on the apron. 

9. The adjustment of the slide and compound rest both for 
straight and taper turning. 

10. The correct method of setting the tool and its adjustment 
in the tool post to obtain the proper angles of rake and clearance 
for the cutting edge. 

11. The method of adjusting the change-gear studs and arm. 
Caution. Always stop this or any other machine for the 

taking of measurements or when it is necessary to leave the 
machine, be it just for a moment. 



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TURNING 201 

Preparatory Processes 

831. Centering. The operations of locating, drilling, and 
reaming centers on lathe work are of importance and require 
careful attention. Various methods, depending upon the shape 
of the piece, are used for locating centers. - Cylindrical pieces, or 
those whose cross-section is symmetrical, are usually centered by 
one of the following similar methods, already described in 
Sec. 712 on '' Laying out cylindrical work*' : centering by dividers, 
centering by surface gage, or centering by hermaphrodite calipers. 
On the ends of the piece, with a distance somewhat greater or 
less than half its diameter, four lines or arcs, inclosing a small 
four-sided figure, are drawn from points on the perimeter. At the 
center of this figure make the center punch mark, and placing 
the piece between the lathe centers, revolve by hand to determine 
the accuracy of the work; an error of ^^ or more is too great and 
should be corrected. Center punch marks may be crowded over 
by slanting the punch before striking. Cup centers and center 
squares are often used for centering where square-ended stock is 
to be had, and centering machines where great numbers of similar 
pieces are to be centered. 

832. Drilling and Countersinking. Having determined the 
approximate centers, a small hole should be drilled at each of 
them. Both ends having been drilled to sufficient depth, the 
60° countersink should be used to ream the holes to the proper 
shape. Care must be taken that the point of the coimtersink 
does not touch the bottom of the hole. The combined drill 
and countersink, with which the hole is drilled and countersunk 
at one operation, has superseded the method where the separate 
drill and center reamer are used. 

Centers may be drilled in the speed lathes, a drill chuck in the 
place of the live center being used to hold the drill. The work 
held against the dead center may then be fed by means of the 
tail-stock screw oV lever. Care must be taken to support the 
piece, otherwise its weight will have a tendency to throw it out 
of position. In working wrought iron or steel some lubricant 
such as lard oil, machine oil or a solution of sodium carbonate 
(sal soda 1 part, water 20 parts) should always be used; other 
metals may be worked dry. If the hole is deep the drill should 
be withdrawn occasionally to clear it of chips and to avoid over- 



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202 ENGINEERING AND SHOP PRACTICE 

heating. Use the highest speed for drilling holes under fV* ^^ 
diameter. When a combined drill and countersink is used to 
countersink work from i'' to S'' in diameter, sizes "B" and "F," 
having body diameters ^^ and ^^^ may be used to advantage. 
The diameter at the base of the cone of the countersink generally 
varies from ^* to %" in work of the above diameter. 

Straight Turning 

841. Manipulation. After the operations of centering and 
countersinking the piece is ready for the lathe. When the piece 
to be turned is cylindrical there are three distinct operations to 
be performed, always in the following order: 

First. Square up the ends. The roughing cut should leave 
the stock ^'^ longer than the finished length. The right-hand 
side tool is used and fed outward from the center. For accurate 
work, re-countersink the centers and finish to the required length, 
setting the right-hand side tool so that its point leaves no mark 
on the work. Backing off the dead center a trifle to allow the 
point of the side tool to just enter the cone of the coimtersink, 
and thus to rid it of the burr or wire edge, is oftentimes recom- 
mended. The objection cited to this method of getting rid of 
the burr is that the stock is liable to run a trifle out of center; 
this latter resulting in the same condition of inaccurate running 
that exists in a piece which has not had its ends squared. 

Second. Take roughing cut over length. Turn the piece to 
^^ larger than the finished diameter, using the diamond-point, 
round-nose, roughing or some similarly ground tool. If, upon 
calipering at several points, the diameters are found to vary, it 
indicates that the centers are out of line, and that the dead 
center must be readjusted. Where several roughing cuts are 
necessary, they should be as heavy as conditions will permit and 
be taken over but half the length of the stock. Reverse the piece 
and turn the other half in the same manner. In this position 
the first half of the last roughing cut is taken without altering 
the adjustment of the tool or moving the slide rest; the work is 
again reversed and the second half of the roughing cut taken. 

Third. Take finishing cut over length. With a keenly whetted 
(stoned) finishing tool or the same tool re-sharpened and 
adjusted, finish to the exact diameter. As was the case with 
the roughing cut, the finishing cut is made over but half the 



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TURNING 203 

length; the piece is then reversed in the lathe and the other half 
finished without altering the adjustment of the tool or slide rest. 
This minimizes any error in the adjustment of the centers and 
insures work of a uniform diameter at the ends. 

If possible, when the work is to be finished by filing and 
polishing, a speed lathe should be used. The speed or hand 
lathe is a lathe similar to the wood-worker's lathe and is designed 
to rotate the work at a higher speed than the ordinary engine 
lathe. In addition to being used for filing and polishing, it is 
often used for drilling and countersinking and such hand turning 
as employs the use of gravers, files and similar tools. 

842. Order of Operations. Always observe the following 
order of procedure when operating the engine lathe for straight 
tiUTiing: 

1. Adjust the work. A dog, a device for transmiting the 
motion from the face-plate to the work, is attached to one end 
of the piece, a drop of oil is put in the countersink at the other 
end, and the tail-stock adjusted for holding the piece between 
the centers. Care should be taken in the adjustment of the 
centers; they must be immovable in the spindle, perfectly clean, 
and in line. Both the taper in the spindle and the centers should 
be wiped clean and dry with new waste before assembling. The 
hardened center should be in the tail-stock spindle, the soft one 
in the live spindle; if both centers are known to be hardened, as 
is often the case, this precaution is unnecessary. The proper 
adjustment is had when the work is free to turn and held just tight 
enough to prevent end motion. The operator should see that the 
tail of the dog does not bind on the bottom of the slot in the face- 
plate. Carelessness in this respect is a frequent cause of error. 
As the work becomes heated and expands, it is often necessary 
to readjust and oil the dead center to avoid turning or twisting 
off its point. In adjusting the tail-stock on the bed, it should 
be clamped in such a position that it will not be necessary to run 
the tail-stock spindle out very far to reach the work, as greater 
rigidity is secured by keeping the spindle well in the tail-stock. 

2. Adjust the tool and carriage. Select the right tool and see 
that it is sharp, i.e., properly ground and whetted. Then adjust 
and fasten it in the tool post in its proper relation to the work, 
giving to the cutting edge the proper angles of rake and clearance. 

3. Determine the speed and feed. Calculate it or consult the 



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204 ENGINEERING AND SHOP PRACTICE 

table, then adjust the belts and gears to obtain this speed and 
feed. 

4. PuU over by hand. With all adjustments made, and the 
tool in its position, pull over by hand to avoid breakage and to 
ascertain the accuracy of the adjustments. 

5. Start the lathe; depth of cut. With all clutches released, 
start the lathe and feed the tool by hand until the desired depth 
of cut is obtained. 

6. Throw in the feed. By means of the feed knobs throw in 
the automatic feed and watch the work carefully to detect any 
irregularity in the working of the machine. Be ready to take 
advantage of every opportunity to save time. Some lubricant 
such as lard oil, machine oil, or soda water should be used when 
turning wrought iron and steel ; other metals may be worked dry. 
The finishing cut should always be very light and made with a 
keenly stoned tool. 

Finishing Processes 

851. Filing. Lathe work, that is subsequently to receive a 
high polish, or to be draw filed, must be filed after the smooth 
finishing cut. Care must be taken not to scratch the work and 
to do just the amount of filing necessary to remove the tool 
marks. Scratching occurs whenever the file "pins" — pinning 
is the collection of little balls of metal between the teeth of the 
file. When the file is passed over the surface of the work these 
particles score or scratch it. See that the file is kept clean, for 
it is impossible to produce good work unless *' pinning" is avoided. 

When work is to be filed to fit a certain gage, or when accuracy 
is desired, it is the practice to leave the work about .002'' large 
after a smooth finishing cut and to remove this stock with what 
is termed a ** float" file. During this operation of finishing, 
pinning may be to a great extent avoided by holding the point 
of the file toward the tail-stock so that it makes an angle with 
the axis of the work; in this position it should be pushed squarely 
across the work, that is, at right angles to the axis of the work. 
During the operation the file appears to be moving toward the 
left; this, however, is not the case. In some cases, filling the 
teeth of the file with chalk will prevent pinning. 

If the work be rotated too rapidly, and especially if it is large, 
the teeth of the file will be instantly worn away. An average 



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TURNING 205 

cutting speed for files is about 50 feet per minute. On the for- 
ward stroke of the file the pressure should be light and uniform; 
returning, the file may roll on the work. Owing to the variation 
of pressure, and to the lack of uniformity in the hardness of the 
metal, it is almost impossible to file a piece perfectly round. 
The work should make four or five revolutions for each stroke of 
the file. When filing to a gage, the end next the dead center 
should be filed first, so that it will just enter; and the operation 
of finishing gradually carried toward the live center, leaving the 
surface such that when the gage is passed over it no perceptible 
looseness is detected. 

852. Scraping. For finishing flat surfaces such as flanges, 
etc., scraping is often resorted to instead of filing. Before com- 
mencing this operation, the workman should review what has been 
said relative to gravers and scrapers in the chapter on "Cutting 
Tools," Sees. 432 and 433. The shank of a lathe tool, clamped 
in the tool post, may be used as an improvised support for the 
scraper. In work of this character it is necessary to take light 
cuts, to hold the scraper firmly, and to work from the center out. 
Chattering may sometimes be prevented by placing a piece of 
leather underneath the tool. 

853. Polishing. Polishing is accomplished in the lathe by 
the use of emery cloth and oil, the coarser grades of cloth first, 
following with the finer. The emery cloth is usually attached to 
a stick which, during the operation, is passed over the tool rest 
and under the work. Considerable pressure may be exerted by 
pressing down on the outer end of the stick, which should be 
moved back and forth continually, in order that the lines cut by 
the particles of emery will be constantly crossing and re-crossing. 
In polishing, the lathe should always be run at its highest speed. 
Watch the dead center; the pressure and high speed may cause 
it to heat and be twisted off. A clasp made of two pieces of 
wood is often used for polishing shafting. 

Taper Turning 

861. Methods of Turning Tapers. There are four methods 
of turning tapers in common use: (1) The dead center is set out 
of line with the live center; this is the ordinary method. (2) A 
lathe provided with a special taper attachment is employed; this 
is a better method. (3) A special taper-turning lathe, in which 



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206 ENGINEERING AND SHOP PRACTICE 

the head-stock and tail-stock may be set at an angle to the line 
of the tool-feed motion, is employed; this is the best method. 
(4) The taper may be turned with the aid of the compound rest. 
The first method is applicable only for outside turning, while the 
other three may be used for turning and boring. 

It is evident that if a conical or taper surface is desired the 
tool must travel along a line at an angle to the axis of rotation 
of the work. This is effected in most lathes by moving the dead 
center to one side or the other by means of set-over screws in 
the tail-stock. In doing this, the first operation is to loosen the 
tail-stock and shove it along the ways until the two centers 
nearly touch. Back off the set-over screw on that side toward 
which the center is to be moved, place a scale between the centers 
and turn the other set-over screw until the proper amount of 
set-over, as indicated by the scale, is obtained. The first set-over 
screw should then be brought up to a firm bearing, after which 
the tail-stock is moved back and clamped in the desired position. 

The amount the dead center should be moved over to turn a 
given taper is dependent upon two things: (1) The angle or the 
amount of the taper, usually given in inches per foot; and (2) the 
entire length of the stock between the centers, regardless of the 
length of the tapered portion. 

Taper is almost always expressed by the difference in diam- 
eter per unit of length; i.e., the ratio 1 in 16. or ^^ to I'', or l" 
to the foot. When the angle of the taper is given in degrees, 
the tangent of that angle gives the ratio, for example, tang. 
3° — 35' = .0626; approximately .0625 which is jY or J'' per 
foot. 

862. Brown & Sharpe and Morse Tapers. The two standard 
tapers in common use are the Brown & Sharpe and the Morse. 
These tapers are designated by numbers, such as Morse taper 
No. 2, the number of the taper indicating a certain diameter or 
size. The Brown & Sharpe taper is supposed to be Y P^r foot, 
while the Morse taper was intended to be f per foot, but unfor- 
tunately the first standards were incorrect and, consequently, the 
taper of the different numbers of the Morse tapers are not the 
same and no one of them is exactly f '^ per foot as was originally 
intended. 

863. Rule for Set-over. Setting over the center changes the 
original distance from the surface of the work to the tool. This 



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207 



increases or diminishes the diameter of the work at that end by 

twice the amount the center is set over. The following is a rule 

for determining the amount of set-over for a given taper: Multiply 

the length of the work between the centers, in inches, by the 

taper per inch and divide this product by two. 

Ijengthof Work X Taper ,. . , , . . . . n- 
^ — ' — ^^- = distance dead center is set out of line 

with live center. The objection to this method of taper-turning 
is the unequal wear on the lathe and work centers, due to the 
set-over. The centers no longer fit the countersink, and while 
at the dead center the work has a rotating motion on the center, 
on the live center it has a reciprocating motion. This unequal 
wear is very annoying as it destroys the truth of the centers and 
consequently that of subsequent work. The only effective way 
out of such a difficulty is to grind the centers. In all cases, after 
turning a portion of the taper, the work should be carefully 
calipered and any error corrected before it is too late. 

864. Theoretical Height of Tool. In taper turning the opera- 
tions, after setting over the tail-stock, are similar to those of 
straight turning. The tool is ground with scant clearance, and 
the keenness obtained by more top rake — because the cutting 
edge must be placed on the center line for the following reasons. 




Fig. 864. 



Suppose we have turned the piece in the figure (Fig. 864) with the 
tool properly set on the center. The line AB is the length of the 
work and consequently the path of the tool. The line A'^' is also 
the path of the tool and shows exactly the amount the tool recedes 
from the axis of the work in traveling along AB, It is evident 
that the travel AB, and the amount A'B' which the tool recedes 
remain the same whether the tool be set high or low. Setting 
the tool at the height C and adjusting for the same diameter at 



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208 ENGINEERING AND SHOP PRACTICE 

the small end, we have the path of the tool along CD and the 
recedence CD' equal to A'B' as before. A circle drawn through 
D' represents the diameter the tool is turning when it arrives at 
D. If we desire to find the diameter the tool is turning at the 
middle of the line CD, we halve the line CD' and through the point 
K' draw a circle which gives the desired diameter; in like manner 
any number of points may be found and transferred to the front 
elevation, when it will be found that the line CIJ is curved. A 
table of tapers per foot and the corresponding angles is given in 
Sec. 529. 

Screw Cutting 

871. The Threading Tool. After reading what has been said 
about the threading tool in Sec. 447, in the chapter on ** Cutting 
Tools," and grinding the tool accordingly, the workman is ready to 
take up the operation of screw cutting in the lathe. It is evident 
from the description, that the same tool cannot be used for both 
right and left-hand threads without changing the clearance. The 
center gage is used to obtain the correct position of the tool. 
In adjusting the tool the cutting edges should always be placed 
on a line with the centers, and so that a center line between them 
is perpendicular to the surface on which the threads are to be 
cut. In this position the tool is clamped firmly in the tool post, 
and care should be taken to see that the dog is tight on the work, 
and that no end play exists. 

872. Change Gearing. The first operation in screw cutting, 
after grinding and stoning the tool, is the selection of the proper 
change gears. On most lathes will be found a table of change 
gears, in the first column of which is given the number of threads 
to the inch to be cut. In the column marked spindle or stud is 
given the number of teeth in the gear which belongs on the spindle 
or stud. In another column will be found the number of teeth 
in the gear which belongs on the lead screw. With such a table 
and ordinary pitches, the selection of the proper gears is an easy 
task. As the intermediate or idler gear is used simply to transmit 
the motion, any size that will conveniently connect the two is se- 
lected. See that no back-lash exists in the gears and also that they 
do not mesh so close together as to cause unnecessary friction. 

When no change gear table is given, or when it is required to 
cut a thread whose pitch is not given in the table, it is necessary 
to calculate the change gears. The first thing to do is to determine 



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TURNING 209 

whether or not the gear on the stud makes the same number of 
revolutions as the spindle. This can be done by counting the 
teeth of the pinion on the spindle and the teeth of the driving 
gear on the stud. The speed, in most cases, will be found to be 
identical and the lathe is geared '*even." If for any reason the 
gears are inaccessible, a trial may have to be made. Put gears 
of equal size on the stud and lead screw and cut a light thread 
on any convenient piece. If the thread proves to be the same 
as that of the lead screw, the lathe is geared **even." If the 
thread is found to be different, use the thread cut as if it were 
the real thread of the lead screw, ignoring in your calculations 
the actual pitch of the lead screw. A rule for obtaining the 
change gears in simple gearing is as follows: 

873. Simple Gearing. — Rule. Write the pitch of the lead 
screw over the pitch of the desired thread in the form of a fraction. 
The numerator will indicate the number of teeth in the gear to 



Simple Gearing 




Fig. 873. — Simple Gearing. 

be put on the stud or spindle, and the denominator will represent 
the number of teeth required on the gear to be put on the lead 
screw; in other words, their ratio. As gears have generally not 
less than 20 teeth, it will be necessary to multiply both numerator 
and denominator by some number that will give a combination 
that can be found among the change gears. For example: the 



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210 



ENGINEERING AND SHOP PRACTICE 



lead screw has 7 threads per inch; we desire to cut a standard 
1" pipe thread of 11 J threads per inch; then 7 over llj represents 
the gears to be used. Multiplying by |, f , or |, we have the 

following combinations from which to select: Jf, JJ, and {|. 

1H^4 46' Hi ^6 69' Hi ^8 92' 

Since, in a train of gears running together the circumferential 
velocity of the teeth is the same in all, and since the circumference 
is proportional to the number of the teeth, we may substitute the 
number of teeth for the circumferential velocities in the formulas; 
thus we obtain our proportions. 

874. Compound Gearing. When the thread to be cut is of 
such an uncommon pitch that the method just explained calls 
for gears one or both of which cannot be found in the assortment 



Compound Gearing j f 





Fig. 874. — Compound Gearing. 

accompanying the lathe, compound gearing must be resorted to. 
In the usual form of compound gearing, two gears of known ratio 
are placed in the position of the intermediate on its stud. The 
following is the rule for determining the change gears for com- 
pound gearing: 

Rule for Compound Gearing, Determine the ratio existing 
between the gears on the idler stud. 



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TURNING 211 

Mesh with spindle gear; generally outside 
Mesh with lead screw gear; generally inside 

Divide the pitch of the screw to be cut by this result; substi- 
tute this quantity for the "desired thread" and proceed as in 
the rule for simple gearing. 

875. Process and Manipulatioii. After properly adjusting 
the change gears throw off the feed belt or feed gear, and bring 
the tool up to the work, adjusting the threading tool stop and its 
stop screw so that the tool will barely mark the surface. Release 
all clutches in the apron; clamp the lead screw nut on the lead 
screw and puU over by hand to determine the correctness of all 
adjustments. Start the machine and, when the point where the 
thread is to stop has been reached, withdraw the tool at once, 
reverse the lathe and allow the tool to travel back to its starting 
point, at which point the lathe is stopped and the work measured 
to see if the pitch is correct. Never reverse the lathe until after 
the tool has been withdrawn free of the cut. Failure to observe 
this precaution will, on account of the backlash (lost motion) in 
the gearing and screw, which allows the work to make a part of 
a rotation before the tool starts back, cause the tool to fail to 
follow the cut, thus spoiling the work or breaking the point off 
the tool. The same trouble is likely to occur if the tool is fed 
into the cut before the work has been allowed to make a few 
turns in the forward direction. 

Too deep a cut has a tendency to break the tool or to bend 
the work, and to prevent difficulty from this cause is the object 
of the stop and "stop screw" mentioned in the preceding para- 
graph. This, "stop-screw" attachment usually consists of some 
combination of a clamp, screw and knurled nut, by means of 
which a minute adjustment may be had. When, after measuring, 
it is desired to take a deeper cut, the stop nut is given a partial 
turn which permits the tool to be advanced the desired depth of 
cut. Another attachment which is of assistance in gaging the 
depth of each cut is the graduated dial, usually found upon the 
cross-feed screw. The first cut should be the longest, letting 
each succeeding cut finish a trifle short of the preceding one; 
that is, the tool is to be withdrawn a little before it has reached 
the position in which it was previously withdrawn. If this 
precaution is not observed, the point of the tool is likely to be 



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212 ENGINEERING AND SHOP PRACTICE 

broken ofif by striking the shoulder at the end of the preceding 
cuts. The length of the imperfect thread thus produced should 
never exceed one half a turn. At the end of larger threads a hole 
is sometimes drilled, or a groove is made around the work with a 
parting tool, into which the threading tool is allowed to run out; 
the last half-turn generally being made by hand. As the depth 
of the thread increases the cuts should become lighter; the finish- 
ing cut, made with a sharp, keenly-whetted (stoned) tool, is very 
light and requires great care; if care is not exercised at this point 
the thread will be either too tight or too loose in the nut. In a 
properly fitted thread no looseness is perceptible, and the nut 
may be turned the entire length of the screw by hand. 

When threading wrought iron or steel, the piece should be 
freely lubricated; lard oil, a weak solution of soap, or a weak 
solution (1 part soda to 20 parts water) of sodium carbonate 
(sal soda) may be used. 

When necessary to remove the work from the lathe, notice 
and mark the slot in the face-plate used for the tail of the dog; 
when replacing, be sure that it occupies its original position. 

Never release the lead screw nut, on short work, until after 
the operation of threading is completed. If it be necessary to 
remove the tool for re-grinding, readjust it as before to fit the 
gage; turn the lathe forward — forward on account of backlash 
— and note the relative position of the cut and the tool point. 
If the adjustment is incorrect, drop out the idler or intermediate 
gear and turn the lathe forward until the proper adjustment is 
obtained; throw in the idler gear and proceed with the cut. In 
case the thread being cut is a very long one much time will be 
lost in waiting for the tool to nm back. In this case the following 
method is often used. The lead screw nut is disengaged and the 
tool moved quickly back to the beginning of the thread; when 
the number of threads per inch being cut is a multiple of the 
number of threads on the lead screw, the thread may be caught 
by engaging the nut at any position, for the reason that when the , 
nut is opened and the carriage moved in either direction, the nut 
will not mesh again until the carriage has moved a distance equal 
to the pitch of the lead screw. If the pitch of the lead screw be 
eight for eight threads, this catches the screw on the next thread; 
for 16 it misses one and catches the second; for 24 it misses two 
and catches the third. If the number of threads on a lead screw 



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213 



be a multiple of the threads cut, the threads can easily be caught 
by inspection; for those threads which cannot be caught by 
inspection the system of marking and stopping, as suggested for 
cases when the stock is removed, is sometimes used. 

876. Order of Operations for Screw Cutting. Observe the 
following order of procedure when screw cutting in the lathe: 

1. Grind the tool. The tool should be ground and whetted to 
suit the thread to be cut; if for a 60° or the standard thread, it 
should be made to fit the 60° center gage. 

2. Select the change gears. After determining upon the proper 
change gears, place them in position, noting that when placed 
neither backlash nor an undue amoimt of friction exists. 




Fig. 876. — Adjusting the Threading Tool. 

3. Throw off the feed belt or feed gear, 

4. Place the rvork. See that the centers are in line, and that 
the dog is securely fastened to the work. Oil the dead center 
countersink, see that no end play exists, and put a chalk mark 
where the thread is to stop. 

5. Adjust the tool. The cutting edges of the tool should be 
placed on a line with the centers. Bring the tool into position, 
using a center gage in adjusting in the manner shown in the 
drawing. 

On lathes which have compound rests the following method 
of grinding and setting the tool may be used to advantage. As 
ordinarily shaped and ground threading tools have little or no 
top rake and for this reason are easily dulled and unsatisfactory; 
by using a tool forged and ground as shown and setting the 
compound rest at an angle of 60° with the axis of the work as 



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214 ENGINEERING AND SHOP PRACTICE 

indicated in the figure (Fig. 876), the disadvantages of the other 
tool are overcome. The tool is given top rake to its cutting 
edge, which operates on but one side of the thread; the tool is set 
in the usual manner with the thread gage. 

6. Clutches and lead screw. With the feed belt off, release all 
the clutches in the apron and clamp the lead screw nut on the 
lead screw. 

7. Adjust the stop. Adjust the stop and stop screw so that 
the tool will barely mark the work. 

8. Pull over by hand. Shift the belt to the correct speed — 
about 15 feet per minute for soft steel or iron — and pull over 
by hand to determine the accuracy of all adjustments. 

9. Start the laihe. Start the lathe and take a very light cut 
to determine the correctness of the pitch. 

10. Proceed with the work. During the operation the cuts 
should become lighter as the depth of the thread increases; the 
finishing cut should be made with a keenly whetted tool and be 
very light. When the work is removed for trial in the gage or 
nut, care must be taken to place it in exactly the same position 
that it occupied before its removal. 

877. Notes on Screw Cutting. Metric screw threads may be 
cut on lathes having inch-divided lead screws, by the use of 
change gears having the proportion 50 to 127, because 127 centi- 
meters = 50 inches (127 x .3937 - 49.9999). 

The lead of a screw is the distance the thread advances in one 
turn; in a single-threaded screw the lead and the pitch are the 
same. In a double-threaded screw the lead equals twice the 
pitch. 

A double thread may be cut, when the number of teeth in the 
spindle gear is even, by dropping out the idler from the spindle 
gear — having first marked a tooth on the spindle gear and a 
corresponding tooth space on the idler — and then turning the 
lathe forward half the number of teeth in the spindle gear. The 
idler is now replaced and the cutting proceeds as before. A 
better method is to have slots, diametrically opposite to each 
other, milled in the face-plate, and to place the tail of the dog in 
one for the first thread and in the other for the second thread. 

A left-hand thread is one whose thread inclines so as to be 
nearer the left hand at the under side, and is cut by inserting a 
second idler to change the direction of rotation of the lead screw. 



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Most lathes are provided with a handle for operating the reversing 
gears under the spindles and it is only necessary to shift the handle 
to perform this operation, i.e., reverse the direction of rotation 
of the lead screw. 

Ordinary Thread Proportions 

88i. The U. S. Standard Thread. The preceding paragraphs 
under the heading "Change Gears" are written with special 




Fig. 881. — U. S. Standard Thread. 

reference to the cutting of the U. S. standard threads, though 
the text is intended to deal primarily with the subject, ** Change 
Gearing" and its application to screw cutting in the lathe. If 
the student has not already read the foregoing text he is advised 
to do so for information on this subject. A table of U. S. stand- 
ard Thread, Bolt and Nut Data is given in Sec. 671, in the chapter 
on "Screw and Pin Data." 

882. The Square Thread. In the square thread the thickness 
of the thread and its depth are each equal to one half the pitch, 



^-W^-A 




Square 
Fig. 882. — Square Thread. 

and its sides are parallel. To obtain the diameter at the bottom 
of a square thread divide one inch by the pitch and subtract it 
from the outside diameter. 

A tool similar in shape to the parting tool is used for cutting 



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216 ENGINEERING AND SHOP PRACTICE 

square threads; its angles of side clearance, however, will vary 
with every diameter and every pitch of thread. Looking at the 
end of the common form of tool used for cutting square threads, 
the cutting portion appears to be twisted to one side, that is, at 
an angle to the perpendicular axis of the tool. This form of tool 
must be so shaped as to run smoothly in the thread, and to this 
fact is due the angularity noticed. The ordinary method of 
finding the amount of "twist " to give the cutting portion of the 
tool is as follows: the circumference of the piece to be threaded 
is laid out on a horizontal line, and at its end is erected a perpen- 
dicular whose length is equal to the pitch; a right triangle is then 
formed by connecting the end of the perpendicular with the end 
of the horizontal line. The angle between the hypothenuse and 
the longer leg of this triangle is the angle which the axis of the 
twisted cutting portion of the tool makes with the perpendicular 
axis. If another triangle be laid out, taking the circumference 
at the bottom of the thread, it is easily seen that this angle varies 
with every cut, and that the method just explained cannot, 
therefore, be theoretically correct; it is, however, the method 
usually employed. It is impossible, for mechanical reasons, to 
cut a perfect square thread with a single tool such as the one 
described; such a tool will cut a thread whose sides and bottom 
are curved. To cut a perfect square thread, the roughing cut is 
made with a single tool, and the sides and bottom finished sepa- 
rately with different tools, each having but one cutting edge and 
that cutting edge placed on the center. When using the single 
tool it must be ground like the parting tool, thinner at the bottom 
than the top to insure clearance. 

883. The 60° V Thread. This thread is similar in shape 
to the U. S. standard with the exception that its side faces meet, 
both at the top and the bottom, in a sharp edge or comer, giving 
rise to the name by which it is sometimes known — sharp thread. 
The side faces of this thread make an angle of 60° with each 
other, the depth of the thread being the sine of the angle (.866) 
times the pitch. The diameter at the bottom of the thread, 
the nominal size of the tap drill, equals the outside diameter 
of the screw minus the quantity 1.732 divided by the pitch 

/ I 732 \ 

( -, 7^ : — r )• This thread is chiefly used for small screws, 

\t breads per mch/ 

etc., and especially for case-hardened set screws. 



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217 




Fig. 883. — 60* V Thread. 



884. The Brown & Sharpe 29"^ Worm Thread. This thread 
is recommended by Brown & Sharpe for worms and hobs and is 
the common thread for worm gearing. The sides of this thread 
make an angle of 29° with each other. The flat at the bottom of 




FiQ. 884. — 2g*» Worm Thread. 



the thread is .31 of the pitch, while the flat at the top is .335 
of the pitch; this, it will be seen, insures a perfect fit on the sides 
of the thread. The depth of the thread is .6866 of the pitch, 
and the diameter at the bottom of the thread is obtained by 
subtracting from the outside diameter the quantity obtained by 
multiplying twice the depth (.6866 x 2 = 1.3732) by the pitch. 
885. The 29° Screw Thread, Acme Standard. On account of 



l^-ttoa^-H 




Fig. 885. ■— 29° Screw Thread, Acme Standard. 



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218 



ENGINEERING AND SHOP PRACTICE 



its having but a small amount of side friction, this thread is being 
used extensively instead of the square thread, where a coarse 
pitch screw is desired. 

The various parts of the 29° Screw Thread, Acme Standard, 
are obtained as follows: 

Width of point of tool for screw or tap thread 
•^^^^ .0052. 



No. of thds. per inch 
Width of screw or nut thread = 



.3707 



No. of thds. per inch 
Diameter of tap = Diameter of screw + .020. 
Diameter of tap or screw at root = Diameter of screw 



-( 1 

\No. of linear t 



Depth of thread = 



thds. per inch 
1 



.020\ 



+ .010. 



2 X No. of thds. per inch 
886. Table of 298 Screw Thread Parts, Acme Standard. 



No. of Thds. 
per In. 
Linear 



1 

n 

2 

3 

4 

5 

6 
7 
8 
9 
10 



DepthofThd.|^''d„;>»T^tTop 



.5100 
.3850 
.2600 
.1767 
.1350 
.1100 
.0933 
.0814 
.0725 
.0655 
.0600 



.3707 
I .2780 
I .1853 
1 .1235 
.0927 
.0741 
.0618 
.0529 
.0463 
.0413 
.0371 



Width at 
Bottom 
of Thd. 



Space at Top 
of Thd. 



Thickness 
at Root 
of Thd. 



.3655 
.2728 
.1801 
.1183 
.0875. 
.0689 
.0566 
.0478 
.0411 
.0361 
.0319 



6293 


.6345 


4720 


.4772 


.3147 


.3199 


2098 


.2150 


.1573 


.1625 


1259 


.1311 


.1049 


.1101 


0899 


.0951 


0787 


.0839 


0699 


.0751 


0629 


.0681 



Fig. 886. 

887. The British Standard or Whitworth Thread. The char- 
acteristic features of this thread are the rounding off of the thread 
tops, the filleting in of the roots and the 55° angle which the 
sides of the thread make with each other. The amount taken off 
the thread top and added to the root is one sixth of the height 



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TURNING 



219 



of a "V" thread whose sides are at an angle of 55** with each 
other. 




British Std. WhitwortVj Thread 



Fig. 887. — British Standard, Whitworth Thread. 

The Trapezoidal Thread. This thread was designed to 
embody the advantages of the square and "V" threads, and for 
use where the pressure on the thread is always in the same relative 
direction. One side of this thread is perpendicular to the bolt 




Fig. 888. — The Trapezoidal Thread. 

axis, while the other side makes an angle of 45° with it. The 
amount taken from the top and added to the bottom of this 
thread is one eighth of the depth of a similar sharp thread; this 
makes the depth of the thread three fourths of the pitch. 



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CHAPTJ^R IX 

T^ORING 
Boring Machines 

911. Boring Defined. Boring may be defined as the produc- 
tion of internal cylindrical or conical surfaces. Boring machines^ 
like most other machine tools, have their origin in the lathe but, 
like them, retain but few of its characteristic details. The two 
classes into which boring machines are divided are the horizontal 
and the vertical. 

912. The Horizontal Boring Machine. The horizontal boring 
machine, in a common type, retains some of the details of lathe 
construction in that the head, with its spindle, cone pulley and 



Fig. 912. — Binsee Horizontal Boring Machine. 

back gears, resembles that of the lathe. Instead of the bed and 
carriage, a table for supporting the work, and having vertical, 
side and longitudinal adjustments, is provided. The end of the 

220 



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BORING 221 

spindle is provided with an attachment for holding either a boring 
bar or a drill. The spindle is splined and so designed that, while 
it rotates with the driving gear, it may be fed through the work, 
either automatically or by hand; this style may also be used 
advantageously for many drilling and heavy milling operations. 

913. ' The Vertical Boring Maclvne. Vertical boring machines 
arc commonly termed boring and turning mills; they bear little 



Fig. 913a. — Baush S(f Vertical Boring Machine. 



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222 ENGINEERING AND SHOP PRACTICE 

resemblance to any other machine tool, save possibly to the planer; 
a common type having the characteristic housings, cross-rail and 
heads which we are wont to see on planers. In place of the platen 
this machine is provided with a horizontal circular table which is, 
in reality, a huge face-plate on which the work is bolted. This 
table is rotated by means of bevel gears, while the tool, held in 



Fig. 9136. — Belts Motor-driven Boring and Turning Mill, 7 ft. 

an adjustable boring bar in the tool head, operates on the work 
which is bolted on the table. The saddles, carrying the heads on 
the cross-rail, may be operated either automatically or by hand, 
as may also be the bars carried in the heads. These heads may 
be swiveled at any angle to provide additional adjustment for the 
tool and to enable taper work to be turned. For face-plate work 
and such other turning as may be handled, the makers claim to 
be able to effect a saving of from 40% to 70% when such work 
is machined on a boring mill. 

914. The Lathe as a Boring Machine. The production of 
internal cylindrical or conical surfaces in the lathe is also termed 



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BORING 223 

boring. The work is either held in a chuck, bolted on the face- 
plate, or fastened to the carriage. In this operation the holding 
or adjustment of the work is of considerable importance and will 
be divided, for convenience of treatment, into three classes: 
(1) Adjustment in chucks, or chucking, Sec. 933; (2) Adjust- 
ment on the face-plate. Sec. 934; (3) Adjustment on the car- 
riage, Sec. 935. 

The Vertical Boring and Turning Mill 

921. Function and Limitations. The function of the boring 
mill is the machining of such cylindrical work as would have to 
be swung or carried on the face-plate of a lathe. It is essentially 
a vertical face plate lathe, so designed as to embody the essential 
characteristics which the lathe possesses for such work, while it 
avoids such inherent lathe defects as the necessary overhanging 
parts and the difficulty of adjusting face-plate work. 

The advantages accruing from a vertical construction are the 
facts that the work is easily placed on the horizontal chuck or 
table; that it is easily centered and fastened there, and that the 
entire weight of the table and work is taken on a large angular 
bearing so constructed as to be self-centering, with a tendency to 
preserve rather than destroy its alignment. 

Regarding the limitations, it may be said that for any cylin- 
drical work, which does not require to be swung on centers, the 
boring mill offers a tool that possesses a few points of excellence 
over that of the lathe for similar work; and as boring mills are 
now equipped with positive feeds and screw-cutting mechanism, 
they not only possess a wide range of usefulness, but for medium 
and large chuck work have superseded the lathe. The same 
degree of accuracy which we receive in the lathe we may expect 
and do receive from the vertical boring and turning mill. 

922. Description of Parts. An advanced type of vertical 
boring and turning machine has the following construction and 
parts: a rigid base or frame which supports the table — and in 
the larger machines the housings — and the entire mechanism; a 
table, in reality a huge face-plate, with its specially designed 
angular bearing, hollow spindle and rotating mechanism; a cross- 
rail ^ supported either on the housings or an extension of the base; 
a saddle or saddles on the cross-rail, carrying one or more swiveling 
boring heads, which latter in turn may be equipped with a turret 



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224 ENGINEERING AND SHOP PRACTICE 

and turret slides; a driving mechanism for operating the table; 
and a feeding mechanism consisting of the various feed cones, 
gears and rods for controlling the movements of the heads and 
tools. Many of the smaller machines are equipped with screw- 
cutting devices and have universal chucks with independent jaws 
built into the table. The table is operated by means of a driving 
cone through the medium of back gears and a bevel gear pinion 
which engages in teeth on its periphery. A 30'' machine has a 
table 28'' in diameter which has 16 changes of speeds. The 
movement of the tool which is held in the head or turret, and 
which operates on the work fastened to the table, is controlled 
by the feed mechanism through the medium of the feed cones, 
gears and rods. The saddles, carrying the heads, turrets, etc., 
on the cross-rail, may be operated either automatically or by 
hand, as may also the slides and turrets. The heads may be 
swiveled at any angle to provide additional adjustment for the 
tool and to enable taper work to be turned. They are provided 
with an absolute center stop so that they may be run to the 
center of the table and clamped, in which position the Morse 
taper, with which they are provided, is concentric with the table, 
permitting the use of small drills, boring bars, etc., without the 
removal of the tool posts from the slide. In the 30'' machine 
the turret is 10^ in diameter and provided with four 24" holes; 
the slide may be set at an angle up to 30° for boring and turning 
tapered work, and possesses a downward movement of 16". The 
feeds, which are positive, range from ^^ to J" horizontally and 
from -^ff" to ^f" vertically, are eight in number and are provided 
with automatic trips. The screw-cutting attachment provides a 
means of cutting from 4 to 12 threads per inch. With this 
machine a double-speed counter-shaft is provided. 

923. Characteristic Operations. It is important to under- 
stand the following operations and adjustments of the boring and 
turning mill before starting to work: 

(1) The correct method of adjusting the tools in the tool post 
or turret, also a knowledge of the turret movement together with 
the use of the socket and the method of removing the tool and 
bars from the spindle or tapers. 

(2) The adjustments of the drive mechanism, back gears, etc., 
so that, after its determination, the correct speed may be given 
to the table and work. 



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BORING 225 

(3) The method of manipulating the saddles and heads so as 
to bring the tool into its proper relation with the work. 

(4) The various methods of securing, after their determination, 
and of controlling the different feeds. 

(5) How to throw in the automatic feeds, and the adjustments 
of the automatic trips. 

(6) A thorough understanding of the screw-cutting mechanism 
and its change gears. 

Boring 

931. Preparation of the Work. The preparation of the work 
for the boring mill is similar to that required when castings are 
machined in the lathe. Very little, if any, laying out is neces- 
sary, the major part of the preparatory process being its adjust- 
ment in relation to the tool. As was the case with the lathe, the 
piece must be set central with the center of rotation, when it is 
blocked up and clamped, either on the table or in the chuck. For 
turning and boring flat work, what has been said relative to 
chucking such work in the lathe applies with equal force here. 
The center of such a piece is first bored, the top faced and as 
much of the outside turned as the jaws will permit, when it is 
turned over and again chucked to the finished portion and fin- 
ished. When possible, drivers — devices to prevent the work 
from turning on the table — should be used in order to prevent 
slipping in the jaws, from the stress due to the tangential pressure 
of the tool. The principles here stated are fundamental, though 
the fastening of irregular pieces may call for some little ingenuity 
on the part of the operator. 

932. Lathe-boring Operations. The operation of boring, after 
the work has been fastened, is comparatively simple. Consider- 
able judgment should be used in the grinding and adjustment of 
the tool; the theoretical height of this tool is below the center 
for the same reason that for outside tools it is above the center. 
For other reasons, however, it is generally placed on the center 
and ground for scant clearance in this position. Where no hole 
is cored, the piece is countersunk with a special tool, and a hole 
drilled with either a flat chucking or an ordinary twist drill, the 
drill being held in a suitable holder. For boring long holes in 
spindles and the like, a hog, or half-round flat nose drill, is some- 
times used. This drill is sometimes used as a bottoming drill. 

I 



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226 ENGINEERING AND SHOP PRACTICE 

In this drill, one side of the cylindrical stock of which it is made 
is cut away, and the other left full size to act as a guide; this drill 
cannot be fed as fast as a twist drill on account of its having but 
one cutting edge. Where rough boring is desired in cored holes, 
a flat drill is used ; the use of this drill necessitates a special holder 
which is clamped in the tool post. 

The student should now read again what has been said about 
boring tools, Sec. 445, in Chapter 4 on "Cutting Tools" and 
related matter in Sees. 946 to 949. The roughing cut — which 
can never be very heavy on account of the spring of the tool 
— should be as heavy as possible. After taking the roughing 
cut, the hole should be calipered; if found to be tapered it will be 
necessary to use lighter cuts. Sometimes a tapered hole may be 
straightened by reversing the feed; this, however, is not good 
practice. Finishing cuts should always be light and taken with 
a fine feed. In turning a pulley, or the flange of a flange coupling, 
it is first chucked for boring and bored; after boring it is reamed 
and forced on an arbor on which it is subsequently finished. 
Where the pulley is small, it may be driven by means of a dog on 
the end of an arbor; where it is large, it is driven by a lug (termed 
a driver) bolted to the face-plate, which engages one of its arms. 

933. Chucking — Adjustment in Chucks. The method of 
holding or adjusting in chucks is best adapted for work that is 
small and regular. The common form of lathe chuck consists of 
a heavy cast^ron disk, on the back of which is bolted a small 
face-plate, threaded to fit the lathe spindle. In the front or face 
of this disc radial slots are cut, through which jaws for holding 
the work are made to slide by means of screws. In fastening the 
chuck to the spindle it should be held carefully in position and 
the lathe turned over by hand until it starts on; no other way should 
be used. Never allow the chuck to come up to the shoulder with 
a bang. A chuck that is tight on the spindle may often be started 
by means of a wooden lever placed between the jaws. Sometimes 
this lever is so placed as to strike the lathe bed when the lathe 
is started backward at its slowest speed. Before assembling the 
chuck and the spindle, the threads on the spindle and in the 
chuck should always be wiped clean and oiled. 

As the matter of adjusting and centering the work in inde- 
pendent and combination chucks is one of try and try, for trial 
the piece is clamped in the chuck and the spindle rotated slowly. 



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BORING 227 

while a piece of chalk or a tool held stationary near it gives indi- 
cation of the amount it is out. 

934. Adjustment on Face-plate. When the character of the 
work is such that it cannot be held in a chuck ^nd can be swung, 
being either too large, too heavy or irregularly shap)ed, it is bolted 
directly to the face-plate. In fastening the work to the face- 
plate, bolts, U-clamps, strips and blocking are used in any manner 
to secure rigidity, the aim being to prevent the work from slipping 
during the operation of boring; in some instances angle plates are 
used: Where the work is such that when bolted to the face-plate 
it is unbalanced — more on one side of the center than on the 
other — it must be counterbalanced by bolting a suitable weight 
on the other side of the face-plate. 

It is almost impossible to clamp two finished surfaces together 
so that they will not slip under the action of the boring tool; 
however, a piece of paper between the surfaces will prove effica- 
cious in obviating this difficulty. 

In all chucking and adjustment of the work, care should be 
taken to see that no projections interfere with either the carriage 
or the ways. 

935. Adjustment on Carriage. This method of fastening the 
work for machining is resorted to when no other method is avail- 
able. Care must be taken that the work be fastened securely, 
as any movement or derangement in adjustment will entail a 
loss of considerable time; paper between finished surfaces will 
again prove effective. It is evident that when the work remains 
stationary the tool must revolve, and to this end boring bars are 
used. A boring bar is generally a shaft, carrying either a fixed 
cutter or a sliding cutter head which carries the cutting tools. 

936. Order of Operations for Lathe Boring. The order of 
procedure for boring in the lathe, after the work is placed, is 
similar to the order of operations for straight turning in Chapter 
8, Sec. 842, and the workman is advised to follow the order 
given there. 

937. Order of Operations for Mill Boring. 

(I) Adjust the work. The adjustment of the work is rather a 
simple operation as compared with its adjustment on the face- 
plate of a lathe, it being manifestly easier to lay a piece down 
than it is to hang it up; and again to secure it when the weight 
of the piece is carried by the machine and not on the securing 



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228 ENGINEERING AND SHOP PRACTICE 

device. The work as it can be, should be trued before the final 
clamping, the horizontal position of the table providing a ready 
means of adjusting the bolts, straps and jacks. Irregular shapes 
such as eccentric discs, offset valves, etc., require no counter- 
balancing, while for manufacturing purposes jigs and fixtures, for 
securing and locating castings, are easily attached to the table. 

(2) Adjust the tool. Select and adjust the tool, noting that it 
is properly ground and whetted. A set of boring tools consists of 
a boring tool, five turning tools, a bar, a 4-lipped drill, a loose 
reamer shank and shell reamer and a tool-holder. 

(3) Adjust the slide and saddle. Bring the head and saddle 
into their proper relation with the work, the tool just over the 
edge of the surface to be operated upon, 

(4) Determine the speed and feed. Calculate it or consult the 
material in Chapter 4, and then adjust the belts and gears to 
obtain this speed and feed. 

(5) Adjust for travel and feed. Adjust the automatic trip dogs 
so as to stop feeding at the proper time, and the feed mechanism 
— coarse or fine as the work in hand demands — so as to obtain 
a maximum output. 

(6) PuU over by hand. With all adjustments made, and the 
tool in its position, pull over by hand to determine the accuracy 
of the adjustments and to avoid breakage. 

(7) Start the machine. Start the machine and feed the tool 
by hand until the desired depth of cut is obtained. 

(8) Throw in the feed. Throw in the automatic feed and 
watch the work carefully to detect any irregularity in the working 
of the machine. Be ready to take advantage of every opportunity 
to save time. 

Chucks, Boring and Chucking Tools 

941. Chucks. As has been stated, the common form of lathe 
chuck consists of a heavy cast-iron disc, on the back of which is 
bolted a small face-plate, threaded to fit the lathe spindle. In 
the front or face of this disc, radial slots are cut, through which 
jaws, for holding the work, are made to slide by means of screws. 

Chucks are classified, according to the number of jaws and the 
method of their adjustment, into independent, universal and 
combination, each kind having either two, three or four jaws as 
desired. 



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BORING 



229 



942. Independent Chucks. An independent chuck is so 
arranged that each jaw may be moved, with its separate adjusting 



fATj 




Fia. 942. — Independent Four-jaw Chuck. 

screw, independently of the other jaws. This style of chuck is 
best adapted to heavy work and work of irregular shape. 

943. Universal Chucks. The universal chuck is constructed 



Fig. 943. — Universal Geared Scroll Chuck. 



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230 



ENGINEERING AND SHOP PRACTICE 



in such a manner that when any one jaw is moved, the others 
move simultaneously in the same direction, a like distance. 
These chucks are best adapted to regular work, as a great saving 
of time is effected by the ease and rapidity with which such work 
may be centered. ' 

944. Combination Chucks. The combination chuck, as its 
name indicates, is a combination of the other two, with its jaws 




FiQ. 944a. — Combination Chuck. 

moving independently or simultaneously as desired.. Owing to 
its greater complexity, this chuck requires a little more care in 
handling; it is used both for regular and irregular work. 



Fig. 9446. — Section of Skinner Combination Chuck. 



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BORING 231 



t'lQ, 944c. — Wesicott Spur-geared Scroll Combination Chuck. 

945. Care of Chucks. As the value of a chuck is dependent 
upon its ability to hold the work firmly and true, it should never 
be abused by hammering or straining. Repeating the points 
noted in Sec. 933: In fastening a chuck to the spindle, it should 
be held carefully in position and the lathe turned over by hand 
until it starts on; no other way is to be used. Never allow the 
chuck to come up to the shoulder with a bang. A chuck that is 
tight on the spindle may be removed by putting a stick of wood 
between the jaws of the chuck and the lathe bed, and starting 
the lathe backward at its slowest speed. Before putting on the 
chuck, see that the threads on the spindle and in the chuck are 
clean; they should always be wiped and oiled. 

946. Boring Bars and Cutters. In boring, when it is necessary 
that the work be stationary, the tool must revolve, and to this 
end boring bars are used. A boring bar is generally a shaft 
carrying either a fixed cutter or a sliding cutter head which 
carries the cutting tools. 

In the drawings. Fig. 946a and Fig. 9466 illustrate types of 
boring bars, while Fig. 946c shows a common form of cutter head. 
Fig. 9466 shows one method of fastening the cutters in a boring bar. 
The pin is made of cast steel, turned to a taper of i" to the foot, 
and hardened. The front edge of the cutter is so placed that it 
will cover about one half of the diameter of the pin hole, and the 
part of the cutter that covers the hole is filed away almost entirely, 
leaving just sufficient stock for the pin to press against when it 
is driven in tight. The cutters are turned while in this position, 
then tiaken out, hardened, replaced and ground to size. A number 
can be made at one time and kept in stock, being first carefully 
marked. 



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232 



KNGINEERING AND SHOP PRACTICE 



-Q>— 



tO- 



H r~ 

A BojdngBar 



--&■ 



-f -H — ii- 



FiG. 946a. — A Common Boring Bar. 
Another Boring Bar wiUi Cotters 




ac3 



Btf I I Z/ 
- 0C3' 



Fig. 9466. -^ Another Bar with Cutters. 




^Q— 



Fig. 946c. — A Cutter or Boring Head. 

A set of cutters for this bar is shown at the right of the bar, 
Fig. 9466. A is a roughing cutter and is held in the bar in the 
manner shown. Sometimes two roughing cuts are necessary for 
each hole, thus requiring two roughing cutters. About .025" is left 
for the finishing cutter, B, whose form is shown with rounded 
cutting edges. It is placed in the same slot as A, but the semi- 
circular groove in it is enlarged so that when the cutter is in its 



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BORING 233 

place the pin does not come in contact with it, the pin being 
used in this case merely to prevent the cutter from falling out of 
the bar previous to its entering the hole. Cutter C is used for 
countersinking or chamfering the opening; this is generally done 
before the finishing cut is taken. 

947. Chucking Drills. Chucking drills are made in a variety 
of styles and shanks, the most noticeable variation frctm the 
ordinary twist drill being a provision for conveying a lubricant 
to the point of the drill. Ordinarily a small circular oil hole, 
connected with a hollow shank, passes through the lands of the 
drill to the point or lips. For drilling cored holes, three- or 
four-groove drills are used; this class of drill is never used for 
drilling solid stock; should it be desired to use it, however, it 
should follow the ordinary two-groove twist drill. Two-groove 
twist-drills should never be used in cored holes, or for following 
another drill. See Figs. 947 a, h and c, pages 234-5. 

g48. Counterbores. Counterboring may be termed the annular 
enlargement of the upper end of a hole; the space between the 
two circumferences forming a shoulder, that is, giving to the 
enlarged portion parallel sides and a flat bottom. Counterbores, 
like other small tools, are made in a variety of styles, sizes and 
shapes. Common commercial bores are provided with straight 
or taper shanks, having at the cutting end a pin or guide, which 
is inserted in the hole to be counterbored. (Fig. 948, page 235.) 
The guides of standard counterbores are made either for the body 
size hole or for the tap drill hole, while the diameter of the counter- 
bore is made for the screw head or for the body of the screw. 
Another form of counterbore is made by inserting and securing a 
tool steel cutter of proper sweep in a rectangular hole, in a round 
bar — oftentimes the ordinary boring bar. 

949. Chucking Reamers. Chucking reamers, like chucking 
drills, are sometimes provided with means for conveying a lubri- 
cant to the cutting lips. For boring and reaming deep cored 
holes, the fluted portion of these reamers is ^* under size and 
is generally made with three grooves. Straight fluted chucking 
reamers, with a number of flutes, are made in standard sizes 
with a rose end or with straight ends in sizes .005 less than the 
nominal diameter. See Figs. 949 a to /, pages 235-6. 



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234 



ENGINEERING AND SHOP PRACTICE 



O 



C I ft 





"7 




3 

c 

Q 

bO 

C 



o 

kl 
o 

C 

o 

§ 
g 
6 

o 




^-1- 









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BORING 



235 



Fig. 9476. — Oil Tube Drill Short Set. 




Fig. 947c. — Oil Tube Drill, Long Set. 



Fig. 948. — Combination Counterbore. 



Fig. 949a. — Three-fluted Chucking Reamer, Short Set. 




Fig. 9496. — Three-fluted Chucking Reamer, Long Set. 



Fig. 949c. — Four-fluted Chucking Reamer, Short Set. 




Fig. 949d, — Four-fluted Chucking Reamer, Long Set. 



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236 ENGINEERING AND 8H0P PRACTICE 



Fia. 949e. — Rose Chucking Reamer, Short Set. 

m 




Fig. 949/. — Rose Chucking Reamer, Long Set. 



Fig. 949<7. — Fluted Chucking Reamer, Short Set. 




Fig. 949A. — Fluted Chucking Reamer, Long Set. 




Fig. 949i. — Shell Reamer Arbor, Short Set. 




Fig. 949;. — Shell Reamer Arbor, Long Set. 



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CHAPTER X 

DRILLING 
Drilling Machines 

loii. Drilling Machines and Operations. There are several 
types of drilling machines on the market; the smaller sizes being 
termed sensitive or sensitive friction drills; the medium or heavy 
sizes are usually termed upright drills; while the terms radial, 
universal, multiple spindle, adjustable spindle, flange, portable 
and pneumatic — usually portable — are all descriptive adjectives 
applied to the various kinds of drilling machines. 



Fia. 1011. — Baush 16-6pindle Double-head Drilling Machine. 

The use of drilling machines has extended from the mere 
work of making round holes in metals, until now it includes such 
operations as: countersinking — a tapering enlargement of the 
upper end of a hole; counterboring — an annular enlargement of 
the upper end of the hole, the space between the two circumfer- 
ences forming a shoulder; reaming — passing a reamer through a 
hole to obtain accuracy and to overcome imperfections; tapping — 
threading the inside of a hole; and spot-facing — a very shallow 
counterbore, barely deep enough to form a smooth shoulder for 
the head of a nut of a bolt. 

237 



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238 ENGINEERING AND SHOP PRACTICE 

I0I2. The Sensitive Friction Drill. A type of this drill con- 
sists of the following essential parts: a base supporting the column 
and driving mechanism; a column which supports the table, 
spindle and feeding device; a movable table on which the work 
may be bolted; a spindle designed to receive and rotate the drill; 



Fig. 1012. — Sensitive Friction Drill. 

a lever feed for raising or lowering the spindle; a friction disc and 
wheel for changing the speed of the drill; and a tight and loose 
pulley for driving the machine. 

In this drill the friction or speed-changing device consists of 
an iron disc and a leather-rimmed w^heel which may be moved 
acro.ss its surface by means of a treadle. The leather-rimmed 



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DRILLING 239 

wheel receives its motion from the driving pulley, transmitting 
it through the friction disc to an oblique shaft, through bevel 
gears to the spindle. 

The spindle, at whose side is a ratchet feed lever, contains at 
its lower end a taper hole to receive the drill shank. A slot through 
the spindle crosses the upper end of the taper, through which a 
drift or key is passed to force the drill from the spindle. The 
table, which is adjustable vertically and about its center, may be 
swung around the column and clamped in any desired position. 
This machine having a maximum capacity of i" holes, is designed 
for such small, light work as may be held in the hand, *' V" chuck 
or vise. By equipping the table with a center, it tnay be used 
advantageously for center drilling and countersinking. 

1013. The Upright Drill. The upright drill is designed for 
drilling holes in the larger, heavier and irregular work of the 



Fia. 1013a. — Prentice 28" Upright Drill with Tapping Attachment. 



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240 ENGINEERING AND SHOP PRACTICE 

ordinary machine shop. While it is true that the lathe is often 
used advantageously for drilling holes in pieces already, or easily 
chucked, the medium-sized drill is better adapted for drilling 
holes in most of the ordinary work of the shop. 

A common type of this drill consists of the following essential 
parts: a base supporting the column, tight and loose pulley, and 



Fig. 1013&. — Barnes Electrically Driven Upright Drill. 

speed cone; a column which supports the table, the sliding head, 
the upper cone, back gears, spindle and feed mechanism; a mov- 
able table on which the work is placed or bolted; a spindle designed 
to receive and rotate the drill; cone pulleys and back gears for 
changing the speed of the drill; a sliding head containing a variable 



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DRILLING 241 

power or hand feed equipped with automatic stop and quick return; 
a device for raising or lowering the sliding head; a device for 
raising or lowering the table; and a tight and loose pulley for driving 
the machine. 

The vertical spindle, the lower end of which contains a taper 
hole for receiving the drill shanks, is rotated from its upper end 
by means of bevel gears from the horizontal shaft which carries 
the back gears and cone pulley. Both of these latter afford 
means of varying the speed of the spindle. The cone pulley above 
is driven by a similar cone on the shaft with the tight and loose 
pulleys situated near the base of the machine. The upper cone 
pulley contains the back gears, which may be thrown into or out 
of action by means of a suitable lever. This lever should never 
be touched while the machine is in motion. Directly underneath 
the spindle, fastened to the column, around which it may be 
swung, is a horizontal table to which the work may be clamped 
or bolted. This table, which is adjustable vertically, may be 
rotated about its axis as well as about the axis of the column. 
The spindle has a vertical movement for feeding the drill, which 
may be operated while running, either automatically or by hand. 
A lever and wheel to the side of the spindle are provided for 
feeding by hand; the power or automatic feed is operated by 
means of a small cone pulley and worm gears, and is equipped 
with suitable latches and stops for throwing it into or out of 
action. In addition to the spindle adjustment for feeding, in 
many machines the construction is such that the entire spindle 
and its feed mechanism may be adjusted vertically on the column; 
when this is the case the drill is said to have a sliding head. The 
spindle, like that of most drills, contains at its lower end a taper 
hole to receive the drill shanks. A slot through the spindle 
crosses the upper end of the taper, through which a drift or key 
is passed to force the drill from the spindle. 

The advantage of this drill over the sensitive drill lies not only 
in the increased capacity and adjustment, but in the fact that 
very heavy, irregular or awkward-shaped pieces may be easily 
adjusted and clamped in position. When using this machine it 
is good practice to bolt the work securely to the table or base, 
both of which are slotted for this purpose. Long bars, '* V "-blocks 
— for holding round pieces — the drill vise and similar articles 
should invariably be bolted to the table, both to insure accuracy 



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242 ENGINEERING AND SHOP PRACTICE 

and to avoid accident. The lubrication of a drill is more easily 
effected when it is held vertically in a spindle than when held 
horizontally in a lathe, for the reason that in the former case the 
oil feeds by gravity into the cutting lips. 

1014. Radial and Universal Drills. The radial drill is de- 
signed to drill holes in such large or irregular work as cannot be 



Fia. 1014a. — Bickford Plain Radial Drill. 

readily placed or bolted on the base or table of the medium 
upright drill. A common type of radial drill consists of a base — 
provided with an extension table — supporting the column and 
speed box; a column which supports the arm and some of the 
speed and feed mechanism; a horizontal arm carrying the head, 
feed mechanism and rods; this arm may be raised or lowered 
either by hand or automatically and may be swung in a full 
circle around the column. The horizontally sliding head carri^ 



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DRILLING 243 

the drill spindle (designed to receive and rotate the drill), the 
feed box, trip mechanism, speed and feed plate, and the various 
operating levers. The speed box attached to the base is designed 
to take the place of the cone pulley and provides four speeds 
instantly by means of a single lever. The feed box attached to 
the head provides, in connection with the back gears, sixteen feeds 



Fig. 10146. — Bickford Universal Radial Drill. 

without stopping the machine. The eight feeds, arranged in a 
geometrical progression ranging from .007'' to .064'^ per revolution 
of the spindle, are operated either automatically or by hand, 
while the spindle is provided with an automatic stop. For such 
large work as cannot be supported on a universal table, the arm 
and head are designed to swivel in such a manner that the drill 
spindle may operate at any angle in any direction; when this is 
the case we have the universal radial drill. The operation of the 



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244 ENGINEERING AND SHOP PRACTICE 

radial drill does not differ materially from that of other drills, 
though the advantages of such a machine tool are obvious. 

Drilling 

1021. Preparation of Work — Laying Out. Chalk the surface 
to be drilled and determine the position of the hole by measuring 
from the center lines or a finished surface, locating the exact 
center of the hole by means of a light center punch mark. About 
this center describe with the dividers a circle whose diameter is 
equal to that of the hole desired. On the circumference of this 
circle make a few — four, six or eight — light punch marks at 
equal intervals. The object of the punch marks being to give 
permanence to the circumference, so that the drill may be brought 
to the proper center after the original center punch mark has 
been cut away. On machined surfaces it is often better to 
describe a circle, slightly larger in diameter than the hole required, 
from the center punch mark and to center the drill from this 
circle. 

When a number of similar pieces are to be drilled, drill jigs 
or templets are used to obviate the expensive operation of accu- 
rately laying out and drilling holes by the method outlined above. 

A hole that is subsequently to be threaded by tapping is 
usually marked thus: ^j^" — 14 Thd. When a hole is so marked, 
the tap drill for this thread should be used, the tap drill, of course, 
being one a trifle larger than the diameter at the bottom of the 
threads. The sizes of tap drills for U. S. standard threads are 
given in the table of ^* U. S. Standard Thread Bolt and Nut 
Data/' Sec. 671, in the chapter on ** Screw and Pin Data." 

1022. Characteristic Operations. It is important to under- 
stand the following operations and adjustments of the drilling 
machine before starting to work: 

1. The correct method of grinding the drill and of holding 
it in the spindle or chuck; also the use of the socket and the method 
of removing the drill from the spindle. 

2. The adjustment of the drive and feed belts and the back 
gears so as to attain, after calculation, the correct speed and 
feed. 

3. The method of manipulating the table so as to bring the 
center punch mark on the work directly underneath the drill and 
of clamping it in this position. 



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DRILLING 245 

4. The various methods of feeding by means of the lever for 
small holes, by using the hand wheel, and automatically by 
throwing in the latch. 

5. The method of reading the depth scale to obtain the proper 
depth of hole. 

6. The manner in which the automatic stop block is adjusted 
to throw the latch which, in turn, stops the feed at the desired 
depth. 

7. How to " throw " the drill. A drill that is off center may 
be drawn back with the center chisel. A groove is chipped, quite 
near the center, down the side toward which the drill point is to 
be drawn. 

8. How to raise the drill spindle while running. This is 
effected by throwing out the feed, grasping the latch handle on 
the long lever with the right hand and raising the spindle with 
the short lever in the left hand. 

1023. Order of Operations. Observe the following order of 
procedure when operating the machine drill. 

1. AdjiLst the work and table. Bolt or clamp the work to the 
table; if held in a vise, the vise should be bolted to the table. 
Select the proper drill, wipe both taper and socket clean, and 
insert in the spindle. Swing the drill table about, and adjust 
the center mark of the hole until it is directly underneath the 
drill point, making sure that the point coincides with the center. 

2. Fasten the table. Clamp the table for position at its center, 
and for height on the column. 

3. Determine the speed and feed. Consult the table (Fig. 1024) 
and the data in Sees. 424, 428 and 429. Adjust the belts to give 
the proper speed and feed; i.e., the ones selected. 

4. Pvll over by hand. With the adjustments made, pull over 
by hand to determine their accuracy. 

5. Start the drill. After starting the machine, feed the drill 
slowly by hand; when the point of the drill has entered the work 
to about half its depth, raise the spindle, blow out the chips, and 
examine to see if the drill is cutting in the center of the circle. 
If the drill has run off it must be drawn back; this is accomplished 
with a center chisel — a light, narrow, round-nosed chisel — with 
which the metal is cut away on the side toward which the drill 
point is to be drawn. A groove is chipped down the side, quite 
near the center, because metal removed there will draw the drill 



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246 ENGINEERING AND SHOP PRACTICE 

farther than when the chipping is done nearer the circumference. 
U the error is great, readjust the table. Now lower the spindle, 
drill the hole a little deeper and correct in the same manner imtil 
the proper adjustment is had. All corrections must be made 
before the full dianieter of the drill enters the metal. 

6. Read depth scale. Note the reading of the depth scale, and 
if several holes of the same depth are to be drilled, adjust the 
automatic stop. 

7. Throw in feed. The automatic feed should be thrown into 
action after the work has been accurately located, and the work 
carefully watched to detect any error or movement that may occur. 

8. When through, raise drill spindle. This may be quickly 
done, as stated above, by throwing out the feed, grasping the 
latch handle on the lever with the right hand and raising the 
spindle with the short lever in the left hand. 

1024. The Speed of Drills. The following data is recom- 
mended by the Cleveland Twist Drill Co. as being applicable to 
the ordinary commercial drills. A feed per revolution of .004" 
to .007" for drills J" or smaller and from .007" to .015^ for larger 
is about all that should be required. This feed is based on a 
peripheral speed of a drill equal to 30 feet per min. for steel; 
35 feet per min. for iron; and 60 feet per min. for brass. It 
may also be found advisable to vary the speed somewhat accord- 
ing as the material to be drilled is more or less refractory. The 
speeds given in the table (Fig. 1024) should not be exceeded 
under ordinary circumstances. 



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DRILLING 










247 








Table 


. OP Cutting Speeds for Drills 




Ft. per 
Min. 


16' 


20^ 


25' 


30' 


35' 


40' 


45' 


50' 


60' 


70' 


80' 


Diam. 


Revolutions per Minute 


Ain. 


917. 


1223. 


1528. 


1834. 


2140. 


2445. 


2761. 


3067. 


3668. 


4280. 


4891. 


J 


459. 


611. 


764. 


917. 


1070. 


1222. 


1376. 


1628. 


1834. 


2139. 


2446. 


A 


306. 


408. 


509. 


611. 


713. 


815. 


917. 


1019. 


1222. 


1426. 


1630. 


i 


229. 


306. 


382. 


468. 


536. 


611. 


688. 


764. 


917. 


1070. 


1222. 


A 


183. 


245. 


306. 


367. 


428. 


489. 


560. 


611. 


733. 


866. 


978. 


i 


153. 


204. 


255. 


306. 


367. 


408. 


468. 


609. 


611. 


713. 


816. 


iV 


131. 


175. 


218. 


262. 


306. 


349. 


393. 


437. 


624. 


611. 


699. 


1 


115. 


153. 


191. 


229. 


268. 


306. 


344. 


382. 


469. 


635. 


611. 


1 


91.8 


123. 


153. 


184. 


214. 


245. 


276. 


306. 


367. 


428. 


489. 


} 


76.3 


102. 


127. 


153. 


178. 


203. 


229. 


264. 


306. 


357. 


408. 


i 


65.5 


87.3 


109. 


131. 


163. 


175. 


196. 


219. 


262. 


306. 


349. 


1 


57.3 


76.4 


95.5 


115. 


134. 


153. 


172. 


191. 


229. 


267. 


306. 


i| 


51.0 


68.0 


85.0 


102. 


119. 


136. 


163. 


170. 


204. 


238. 


272. 


iJ 


45.8 


61.2 


76.3 


91.8 


107. 


123. 


137. 


163. 


183. 


214. 


246. 


i| 


41.7 


55.6 


69.5 


83.3 


97.2 


111. 


126. 


139. 


167. 


196. 


222. 


11 


38.2 


50.8 


63.7 


76,3 


89.2 


102. 


115. 


127. 


163. 


178. 


204. 


i| 


35.0 


47.0 


58.8 


70.5 


82.2 


93.9 


106. 


117. 


141. 


166. 


188. 


n 


32.7 


43.6 


64.5 


66.5 


76.4 


87.3 


98.2 


109. 


131. 


163. 


175. 


n 


30.6 


40.7 


60.9 


61.1 


71.3 


81.5 


91.9 


102. 


122. 


143. 


163. 


2 


28.7 


38.2 


47.8 


67.3 


66.9 


76.4 


86.0 


95.5 


116. 


134. 


163. 


2i 


25.4 


34.0 


42.4 


51.0 


69.4 


68.0 


76.2 


85.0 


102. 


119. 


136. 


21 


22.9 


30.6 


38.2 


46.8 


63.5 


61.2 


68.8 


76.3 


91.7 


107. 


122. 


2i 


20.8 


27.8 


34.7 


41.7 


48.6 


56.6 


62.5 


69.6 


83.4 


97.2 111. 


3 


19.1 


25.5 


31.8 


38.2 


44.6 


51.0 57.3 


63.7 


76.4 


89.1 


102. 












Fio. 


1024. 













Drills 
103 1. Characteristics of a Drill. Of the several forms of 
drills used in the machine shop, the primitive, simply made 
flat drill is the cheapest and easiest to make, while the twist drill, 
possessing most of the advantages and few of the defects of the 
other types, has come into almost universal use. The essential 
characteristics of a drill are as follows: (1) It must have one or 
more cutting edges. (2) It must have a central guiding or leading 
point; this leading point is usually secured by grinding the cutting 
edges at an angle with the axis of the drill, generally between 
50 and 60 degrees. (3) The cutting edge must have ample clear- 
ance. (4) There must be a suitable shank for holding the drill. 



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ENGINEERING AND SHOP PRACTICE 



1032. The Flat Drill. In order that the flat drill may pro- 
duce accurate work, it is essential that the cutting end be sym- 
metrical in every respect. Improperly formed edges tend to 
produce holes that are out of position, rough, oblique, holes that 
are larger than intended and holes not round. From a glance at 




Fig. 1032. — Flat Drill. 

the drawing (Fig. 1032) it will be seen that the planes represent- 
ing the clearance angles intersect in a line perpendicular to the 
axis of the drill, and that when the drill is rotated, the action 
here is a scraping instead of a cutting one. It becomes evident 
that the best results will be obtained when this scraping edge 
is short; therefore, the thinner the drill, when sufficient thick- 
ness is had to support the cutting edges, the better. 

1033. The Lipped Drill. In this drill, in order to produce 
keenness and to give what, in a lathe tool, would be called top 




Fig. 1033, 



rake, the cutting edge is ground as shown in the drawing. What 
is still better is to twist it as shown in the other drawing; this 
produces a spiral that assists in carrying the chips away from 



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DRILLING 



249 



the cutting edge, anticipating, in some respects, the ordinary 
twist drill. 

1034. The Scraping Edge Drill. The point of this drill is 
similar to that of the ordinary flat drill, with the exception that 



Fig. 1034. —Scraping Edge Drill. 

it is ground for clearance on both sides, producing an edge similar 
to that of a cold chisel. The one advantage of this drill lies in 
the fact that it works equally well backward and forward. 

1035. The Half-round or Hog-nose Drill. In this drill, one 
side of the cylindrical stock of which it is made is cut away and 
the other half is left the full size of the hole to act as a guide. 
The cutting edge should be ground perpendicular to the axis 




Fig. 1035.— Half-round or Hog-nose Drill. 

of the drill and be given a clearance of 5°. It is important that 
this drill, as it possesses no central leading point, be started 
true; when this is done a hole of any depth may be bored smooth 
and true. Some authorities state that for boring parallel accu- 
rate holes this drill is unsurpassed. This drill may also be used 
for squaring the bottom of holes drilled with drills having a central 
leading point. 

1036. The Modified Hog Nose. — " D" Drill. A modification 
of the hog-nose drill is shown in the figure. This drill in its 
simplest form consists of a round bar of the diameter of the 
hole required, one side of the end of which is relieved — cut away 



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ENGINEERING AND SHOP PRACTICE 




Fia. 1036. — Modified Hog Nose 



DriU. 



— to give clearance; in other respects this drill is similar to the 
hog-nose drill described above. This drill in some one of its 
modifications is generally used for boring lathe spindles, hollow 
shafts, guns and the like. What has been said in reference to 
the grinding and operation of the hog-nose drill applies with 
equal value to this modification of it. 

1037. The Straight-fluted Drill. The commercial drill of this 
variety is made of round stock generally, with two straight flutes 




a 



7 



Fig. 1037a. — Straight Shank Straight-fluted DriU. 




FiQ. 10376. —Taper Shank Straight-fluted Drill. 

running parallel to the axis of the drill. This drill is usually 
ground similar to the twist drill or flat drill and possesses advan- 
tages over them for the softer metals such as babbitt and the 
copper alloys. A straight-fluted drill will be found excellent for 
drilling thin plates and similar work. 

1038. The Twist Drill. Ordinary twist drills are made of 
round stock and helical fluted with a milling cutter. To prevent 



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DRILLING 



251 



undue friction on the sides of the hole, the metal between the 
flutes is backed ofif in one of the ways shown in Fig. 10386; just 




Fig. 1038a. — Taper Shank Twist Drill. 




Fig. 10386. — Method of Relieving Drill Lands. 

enough surface is left, however, to form a bearing and guide for 
the drill. What has been said of the irregularities produced 
by the imperfect grinding of flat drills applies with equal force 
to twist drills. By the use of a drill grinder these difficulties 
are almost entirely obviated. 

1039. Special Drills, Countersinks and Reamers. The fol- 
lowing group of half-tones. Figs. 1039a to 1039/, together with 
their designations, will give the reader some idea of the various 
commercial specialties to be had of the drill makers. 






Fig. 1039a. — Flat Drill with Ratchet Shank. 




Fig. 10396. — Taper Shank Left-hand Twist Drill. 



Fig. 1039c. — Straight Shank Oil Groove Twist Drill. 




Fig. 1039(i. — Bit Stock Countersink. 



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ENGINEERING AND SHOP PRACTICE 




Fig. 1039e. — Combined Drill and Countersink. 





Fig. 1039/ — Center Reamers. 

Drill Shanks, Sockets and Collets 

1041. Drill Shanks. There are several styles of drill shanks 
in ordinary use; the most common, however, are the straight and 
taper shanks. The taper shank drills, while more costly than 
the straight shank, possess many advantages over them; when 
inserted in a socket they will not drop out; wear in the drill 
spindle does not necessarily produce a derangement of the cutting 
edges of the drill; and in a properly fitted, clean socket the drill is 
always tight. At the end of the taper shank — at the top — a flat 
portion or tang fits into a slot in the spindle and prevents the 
drill from turning in the socket. The tapers in common use are 
the Morse tapers, numbered from one to six inclusively, having 
the dimensions given in the following table. ( Fig. 1042. ) 

Note, The Morse taper was intended to be f '^ per foot, but 
unfortunately the first standards were incorrect, and consequently 
the different numbers of the Morse tapers are not the same, 
and no one of them is exactly i" per foot as was originally 
intended. 



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DRILLING 253 

1042. Morse Taper Shanks. Dimensions in Inches. 




DIMENSIONS 



NO. 


A 


B 


c 


D 


E 


TAPEB 

IN 13 

INCHES 


1 


2^}Um. 


2'. win. 


.353 in. 


.475 in. 


V»fl4in. 


.600in. 


2 


QSr 
O/M 


2^. 


.563 


.700 


M 


.602 


3 


3/ifl 


s% 


.763 


.938 


'A. 


.602 


4 


514 


AH 


.991 


1.231 


"/« 


.623 


5 


63^ 


5Jii 


1.440 


1.748 


H 


.630 


6 


m 


8U 


2.064 


2.4d4 


H 


.626 



Fia. 1042. ~ Standard Morse Tapers. 



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ENGINEERING AND SHOP PRACTICE 



1043. Drill Sockets and Collets. Because all sizes of drills 
are not made with the same size of taper shank, drill sockets or 
collets are used. Drill sockets are tapered bushings, the outside 
being made to fit one size of taper shank drills, and the inside 
another size of taper. Collets are used for holding taper shank 
drills in spindles intended for straight shanks, and vice versa. 
By inserting a drift or center key, whose taper is 1}*' per foot 
(8° 190, in a suitable hole provided in the spindle and sockets 
the drill may be forced out of them. (Figs. 1043 a, 6, c, d and 
e, show the various drill sockets and collets, and the method 
of removing the drill from the spindle or socket.) 




Fig. 104;Ja. — Rough Drill Socket. 




Fig. 10436. — Fitted Taper Shank Drill Socket. 




Fig. 1043c. — Sleeve or Shell Socket or Collet. 

Drill Chucks 

1051. Light Drill Chucks. For the smaller straight-shank 
drills, and for light drilling, some form of drill chuck affords an 
excellent method of holding the drill. For the character of work 
employing the use of sensitive drilling machines and speed lathes, 
a light chuck similar to the Almond is generally used. This 
type of chuck is held in the spindle by means of a taper shank, 
which is either screwed or forced into a corresponding thread or 
taper in the chuck body. The chuck jaws, operated by a single 
nut, move in three holes or passages which converge toward the 
center line of the chuck. Upon any movement of the knurled 



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PRILLING 



255 



Fig. 1043d. — Section of Drill Socket showing 
how the driU is removed by the drift. 




FiQ. 1043€. — Drift or Center Key. 



Fig. 1051. — The Almond Drill Chuck. 



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256 ENGINEERING AND SHOP PRACTICE 

collar in which the nut is held, the jaws — so shaped that they 
are always parallel at that portion which grips the drill — open 
or close to accommodate the various sizes of drills. 

1052. Heavy Drill Chucks. The Pratt and Hartford chucks 
are excellent examples of the heavier type of drill chucks. The 
Pratt chuck contains two jaws opposite each other, controlled by 
a single right and left screw. These jaws move in a slot or guide- 
way cut across the lower portion of the chuck body. Above the 



Fig. 1052.— The Pratt Drill Chuck. 

jaws, and resting on them, is a plate containing a slot into which 
the drill tang may be inserted; this prevents the drill from slip- 
ping. The faces of the jaws are always parallel and contain 
grooves to obtain a uniform distribution of the pressure. Below 
the jaw, screwed to the chuck body, is a plate containing a central 
hole, whose diameter indicates the maximum capacity of the 
chuck. 

1053. Tapping Chucks. Where a great deal of rapid, accurate 
tapping is to be done, a machine drill, fitted with a special chuck, 
is generally used ; when such is the case the spindle of the machine 
is fitted with one of the several automatic reverse tapping chucks 
now on the market. In one form of these chucks the tap is 
automatically reversed and backed out after it has run a desired 
depth; in another form, the tap continues to run forward until 
a certain resistance is offered, when a reversing gear is thrown 
into action and the tap backed out. In this second type, this 
action occurs in either event, whether the tap bottoms or 
sticks. 



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DRILLING 



257 




Fig. 1053. — St. Louis Reversing Tapping Chuck. 



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CHAPTER XI 

GRINDING 

nil. Grinding Operations. Hand and Machine. The oper- 
ations of grinding may be divided into two classes, hand and 
machine. 

Hand grinding defines such abrasive operations as are per- 
formed when the object to be ground is held and pressed against 
the wheel or stone by hand. In the small machine shop, such 
grinding consists in the removal of irregularities from castings, in 
the rough rapid reduction of small areas and sometimes in the 
grinding of shop tools. 

Machine grinding may be defined as the production — using 
abrasive processes — of accurate, plain, cylindrical and conical 
surfaces by automatic or semi-automatic machines; the accuracy 
of the surfaces being dependent, rather upon the accuracy of the 
machine, than upon the skill of the operator. The various classes 
into which machine grinding is usually divided are: surface grind- 
ing, disc grinding, tool and cutter grinding, and cylindrical and 
conical grinding. 

1 1 12. The Dry Grinder and Attachments. A simple form of 
hand-grinding machine is the common dry grinder. The ordinary 
type of this machine consists of a column or base supporting the 
bearings in which revolves a spindle, designed for carrying the 
driving pulley and two emery wheels, one on each end. Suitable 
adjustable rests, on which the work is supported during the 
operation, and a water cup into which it may he dipped when 
heated, are also provided. Grinders of this type are made in a 
wide range of sizes, and carry wheels from three inches to three 
feet in diameter. Dry grinders are sometimes equipped with 
attachments for truing the wheel, for hand surfacing and for 
buffing. 



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GRINDING 259 



Fia. 1112. — Blount Dry Grinder. 



1 1 13. The Disc Grinder. Disc grinders are designed for the 
production of accurate work by hand, and to obviate the diffi- 
culty — that of keeping the surface of an emery wheel true — 



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260 ENGINEERING AND SHOP PRACTICE 

inherent in all emery grinders, the characteristic difference between 
this and the ordinary dry grinder being the substituting of metal 
discs for emery wheels. The grinding is effected by means of 
emery cloth attached to the sides of the discs; these discs, varying 



Fia. 1113. — Gorton Universal Flat Surface Disc Grinder. 

in thickness from i" to J'', are accurately ground, parallel and 
true, and in some instances carry on their sides spiral grooves; 
the object of the grooves being (the emery cloth conforming to 
the surface) to provide a space into which the particles of emery 
and metal may be deposited, thus preventing scratching and 
scoring. 

1 1 14. The Wet Grinder. Wet grinders are designed to pre- 
vent the heating and the consequent loss of temper which is 
likely to occur where the tools are ground dry. This type of 
emery grinder is used almost exclusively for tool grinding, and 



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GRINDING 261 

is similar to the dry grinder, with the exception that it is provided 
with a device for supplying a desired quantity of water to the 
wheel, and guards for preventing the water from being thrown 
where it is not wanted. This grinder is never used for rough 
work, and should be kept true to obtain the best results. Wet 
grinders are sometimes designed with a universal tool holder for 



Fio. 1114. — Whitney Wet or Water Tool Grinder. 

holding lathe and planer tools at certain desired angles with the 
wheel. By consulting the chart furnished with such a machine 
the holder may be set, and the tool ground with the correct angles 
of reak and clearance, thus eliminating the personal equation and 
reducing the product to a standard. 

1 1 15. The Universal Cutter and Reamer Grinder. The adapt- 
ability and extensive use of rotating cutters in milling and kindred 
operations have led to the development of a specially designed 
machine, universal within its capacity for the sharpening of all 
sorts of cutters, reamers, etc. The machine is provided with a 
full complement of wheels and attachments for performing these 
operations, and is adapted for doing a limited amount of both 
internal and external cylindrical and conical grinding. 



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262 ENGINEERING AND SHOP PRACTICE 



Fig. 1115. — Brown & Sharpe Universal Cutter and Reamer Grinder. 

1116. The Drill Grinder. To obviate the necessity of em- 
ploying a skilled operator who could correctly perform by hand 
the difficult operation of grinding a drill, the twist drill grinder 
was invented. In this machine a holder or trough is so adjusted 
and swung in its relation to the wheel, that when the drill is held 
in it, the cutting lips are ground at a determined angle and given 
the proper amount of clearance. 



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GRINDING 263 



Fia. 1116. — Worcester Inverted Wet Drill Grinder. 



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264 ENGINEERING AND SHOP PRACTICE 

Universal Grinder 

II2I, Functions and Limitations. The chief function of the 
universal grinder is the automatic production of accurate cylin- 
drical and conical surfaces. By the use of special attachments 
furnished with these machines the operator is not only enabled 
to produce such work and perform a number of internal grinding 
operations but also accomplish a variety of such intricate grinding 
operations, as are usually performed on a universal cutter and 
reamer grinder. Reamers, gear cutters, face, side and end mills, 
centers, gages and chuck work may be ground and facing opera- 
tions performed by the use of these attachments. 



Fig. 1121a. — Brown & Sharpe Universjul and Tool (irinding Machine (Front). 



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GRINDING 265 



Fig. 11216. — Rear View of Fig. 1121a. 



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266 



ENGINEERING AND SHOP PRACTICE 



15 



/'^ 



Fig. 1121c. 



Brown & Sharpe Machine, Index to Parte Controlling 
Adjustments and Movements. 



Index to Parts Controllino Adjustments and Movements 

Thumb Screw for clamping 
Head-stock Spindle. 
Setting Pin. 
Live Center Pulley. 
Dead Center Pulley. 
Adjusting Screw for Foct- 
stock Spindle. 

Clamp for Foot-Stock Spin- 
dle. 

Adjustable Table Dogs. 
Screws for fine adjustment 
of Table Dogs. 
Hand Wheel for vertical ad- 
justment of Wheel Slide. 
Pin for locking Reversing 
Lever. 



No. 


7. 


Knob for clamping Elevating 
Screw Hand Wheel, after set- 


No. 


16. 






ting. 


No. 


17. 


No. 


8. 


Hand Wheel for Cross Feed. 


No. 


18. 


No. 


9. 


Thumb Screw for controlling 


No. 


19. 






fine or coarse Cross Feed. 


No. 


20. 


No. 


10. 


Thumb Screw for fine Cross 










Feed. 


No. 


21. 


No. 


11. 


Bolt for clamping Swivel 










Table. 


No. 


22. 


No. 


12. 


Spring Knob for engaging 
fine adjustment of Swivel 


No, 


.23. 






Table. 


No. 


,24. 


No. 


13. 


Thumb Screw for fine adjust- 










ment of Swivel Table. 


No. 


.25. 


No. 


14. 


Hand Wheel for Table Feed. 






No. 


15. 


Lever for controlling Table 
Feed. 







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GRINDING 267 

The grinding machine is the most sensitive detector of error in 
work of any metal working machine in existence. The variation 
of sparking in grinding an arbor, as often seen, to the minds of 
many would indicate the work to be very much out of true; the 
amount of inaccuracy, however, may very often be less than 
one-fiftieth of one thousandth of an inch. It is possible to take 
a cut one five-millionth (.000,005'^) of an inch in depth. When 
turned stock is to be finjphed by grinding, ^^ to .Ol'^ is sufficient 
stock to allow for the operation. 

1 122. Description of Parts. The universal grinding machine, 
formerly termed a grinding lathe, is one with which, within the 
capacity of the machine, all classes of grinding are accomplished. 



Fig. 1122. — Landis Universal Grinder. 

An ordinary form of the universal grinder consists of the following 
parts: a column or base enclosing the carriage, operating an auto- 
matic reverse mechanism and supporting the wheel carriage and 
table which carries the head- and tail-stock; a table or bedy adjust- 
able for taper grinding, which carries the head-stock, the foot- 
stock and water guard; a wheel carriage , sliding in guide ways at 
the back of the column and carrying the slide and wheel; a 
sniveled slides containing the rotating emery wheel and carrying 



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268 ENGINEERING AND SHOP PRACTICE 

its adjusting mechanism, its water casings and delivery hose; a 
smiveling head^stock, mounted on the table, carrying the spindle, 
its driving pulley, a center and dead center pulley for rotating 
the work on the centers; and a foot-stocky adjustable on the table, 
and provided with a lever adjusted spindle and center and a 
center relieving nut. 

In this machine the wheel, revolved from an overhead driver, 
moves along the rotating work during the grinding operation; 
in some machines, howeVer, the reverse is the case. Both centers 
in this class of grinders are dead centers because, should the work 
be revolved by a spindle, it is found that it partakes of any lack 
of roundness and accuracy inherent in the spindle. A dead center 
puUey provides a means of rotating the work on the centers, thus 
eliminating any errors that exist because of lack of truth in the 
spindle. The spindle is threaded to receive the chuck and is 
provided with a pulley by which it may be rotated when desired, 
and a stop pin to be inserted when operating on dead centers. 
The foot-stock may be likened to the tail-stock of an engine 
lathe, and serves the same purpose. Its spindle, carrying the 
center, is provided with an adjustable spring tension which holds 
the center in the work with a certain pressure, thus obviating any 
error that would be due to springing, should the operator jam 
the center; and providing the means of automatic adjustment 
for any expansion that may take place in the work. 

Ordinarily the wheel is fed to the work by hand by means 
of a suitably graduated disc and handle, but the advantages of 
the automatic cross-feed attachment, with which some machines 
are provided, are obvious. It not only relieves the operator of 
the necessity of moving the wheel up to the work at the end of 
each traverse, but automatically stops feeding when the desired 
diameter is reached; and furthermore it enables one operator to 
tend to several machines. Contrasting the operation of such a 
cross-feed with that of the lathe, we find it to be entirely different 
in construction and operation. A grinder feed must advance the 
wheel toward the axis of the work a certain amount at the end 
of the traverse, and not constantly as in a lathe. It must also 
perform this operation a certain predetermined number of times 
and stop automatically. Such an attachment may be purchased 
for any of the leading makes of grinders, and on account of the 
uniformity of its operation it not only maintains a proper condi- 



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GRINDING 269 

tion of the wheel, increasing its sizing power, but also, by the stop, 
prevents the production of work that is too small. 

1 123. Characteristic Operations. It is important to under- 
stand the following operations and adjustments of the universal 
grinder before starting to work: 

1. How to obtain, after its determination, the proper emery- 
wheel speed; the correct work speed, i.e., the number of revolu- 
tions necessary to secure for the particular diameter a perimeter 
speed of about one hundred feet per minute — this will vary, 
of course, with the method and character of the work — and the 
correct rate of wheel traverse; this latter should be faster for 
finishing cuts, which should be always light, than for roughing 
cuts; if, however, the face of the wheel is not sufficiently parallel 
with the surface of the work, a slower traverse should be used, 
otherwise the work will be ridged. 

2. How to start the emery wheel; this is effected by pulling 
the weighted cord which shifts the belt to the driving pulley. 
How to start the work; this is effected by means of a shipper-arm 
attached to a clutch. However, different methods obtain in effect- 
ing these operations. 

3. The method of adjusting the work in the grinder, not only 
for the operation of grinding on dead centers, but also for such 
rough and chuck work as requires the use of the live center. 

4. The various adjustments of the foot-stock; how to clamp 
it in its proper position on the table; the adjustment of the center 
relieving nut to secure the action of the spring tension; and how 
to remove the work without altering the adjustment of the foot- 
stock. 

5. The adjustment of the table by means of taper-adjusting 
and clamping screws, for taper and conical grinding. 

6. The adjustment of the water guards on the table, of the 
delivery nozzle in its relation to the wheel and work, and the 
proper quantity of water for the operation. 

7. The adjustment of the stationary rests and sliding back 
rests; the clamping of the stationary rest on the table and the 
sliding rest on the wheel carriage. 

8. The automatic traverse mechanism and how to secure, by 
means of the screw dogs on the traverse wheel, the proper length 
of traverse. 

9. How to instantly start or stop the traverse, either by 



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270 ENGINEERING AND SHOP PRACTICE 

means of the automatic traverse knob, the traverse lever or the 
shipper arm. 

10. Various adjustments of the slide, the wheel spindle, and 
the feed mechanism; an average feed is about .OOl'^ and feeding 
should occur only at the end of each traverse. 

Caution. Always stop this or any other machine for the taking 
of measurements, or when it is necessary to leave the machine, be 
it just for a moment. 

Grinding — Hand Abrasive Operations 

1131. Hand Grinding. Hand grinding, as has been stated, 
defines such abrasive processes as are performed when the object 
to be ground is held and pressed against the wheel or stone by 
hand. In the small machine shop, such grinding consists in the 
removal of irregularities from castings, in the rough, rapid reduc- 
tion of small areas and sometimes in the grinding of shop tools. 

1 132. Hand Surfacing. The common type of dry grinder is 
sometimes equipped with an adjustable table through which the 
emery wheel projects; this table being provided with a movable 
gage. With such a device, though the surface produced be only 
approximately fiat, hand-surfacing may be done with profit. 

1 133. BufiBng. Buffing may be defined as the operation of 
obtaining — by means of rapidly revolving cloth or felt discs — 
a certain grainless finish. The term polishing may refer to the 
production of any bright finish. Buffing wheels or buffs are 
made of either felt, or of several discs of cotton cloth sewed 
together so as to present their edges to the work. By substituting 
a buffing wheel for one of the emery wheels of a dry grinder, 
many buffing operations may be successfully performed. Emery 
cake, a mixture of very fine emery and tallow, is sometimes used 
on buffing wheels to facilitate the operation. 

Grinding — Machine Abrasive Operations 

1141. Preparation of the Work. C. H. Norton makes the 
following remarks in the American Machinist: 

**Late experience shows it to be practicable to remove one 
cubic inch of steel per minute from cylindrical work by grinding 
with suitable wheels. It should not be inferred from this that 
it is more profitable to leave a large amount of stock on purpose 
to grind it off with emery wheels; but that in many cases it 



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GRINDING 271 

is not practicable to make a quick lathe cut good enough to 
allow of closer turning on account of spring; and if the lathe cut 
is not a quick one, at high speed and coarse feed, the grinding 
wheel will beat it in the simple matter of removing stock, to say 
nothing of the better surface produced. It is no longer profitable 
to turn nicely to size in a lathe, when by the use of grinding 
wheels we can produce better work at much less cost. 

^'It is also possible to grind many pieces without turning at 
all more cheaply than to turn them; others require very rude 
turning only before grinding, while some require closer turning to 
show economy. For these different classes of work it is necessary 
to select the wheel to produce the largest saving in time, and best 
results in quality." 

To be specific, we might say that the piece that is subsequently 
to be ground should leave the lathe from .010'^ to .030'' larger 
than the finished ground diameter. 

Good, clean and accurately shaped centers on centered work 
are essential to all successful grinding operations, and care should 
be taken to see that both centers are clean, and properly oiled. 

1 142. Discussion and Classification. Machine grinding, as 
has been stated, may be divided into several classes; such as 
surface grinding, disc grinding, tool and cutter grinding, and 
cylindrical and conical grinding. 

It may be stated that the vital difference between the grinder 
and other machine tools lies in the fact that the cutting tool of 
steel is replaced by a rapidly rotating wheel made of some abrasive 
material, such as emery, corundum, alundum, or carborundum. 
The class of grinding to which most of our remarks will be 
devoted is cylindrical and conical grinding. 

1 143. Principles and Advantages Involved in Cylindrical and 
Conical Grinding. Cylindrical and conical grinding refer to the 
grinding of solids of revolution, a solid of revolution being a 
solid generated by the revolution of some plane figure about a 
line as an axis; thus a right cone is generated by the revolution 
of a triangle bout one of its sides. The fundamental principle 
underlying the grinding of solids of revolution is the application 
of thousands of cutting points to the surface of the work, while 
it is being slowly rotated about its axis. In consequence of each 
cutting point removing but an exceedingly small particle of 
metal, the pressure due to the cutting operation is very light. 



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272 ENGINEERING AND SHOP PRACTICE 

Because of this fact, the disturbance of the axes of the work and 
the wheel is correspondingly small, insuring great accuracy in 
the work. 

It is evident that if a truly cylindrical surface is desired, the 
grinding wheel must traverse along the surface of the rotating 
solid in a straight line parallel to its axis of rotation. If the line 
of motion of the wheel is at an angle to the axis of rotation of 
the solid, it will be ground conical. An emery wheel having a 
diameter of IS'' x i" face, when running at its ordinary speed, 
presents approximately 2,500,000 cutting points to the work in 
one minute; though each particle is minute, the aggregate amount 
is comparatively large. Taking into consideration the fact that 
in modern grinding machines the cutting points pass over from 
one to four square feet of surface per minute, it is readily seen 
how these numerous cutting points can remove, as recent practice 
shows, about one cubic inch of steel per minute from cylindrical 
work, this being about 17 pounds per hour. 

The advantages of machine grinding are: first, the economical 
production of finished sized work; second, the great accuracy 
obtainable by this method. The first advantage is to-day the 
most important one. 

1 144. Discussion of Speeds, Traverse and Temperature. In 
the Landis universal grinding machine, No. 1, the emery wheel, 
which is lO'^ in diameter, has five changes of speed from 1529 to 
3301 revolutions; while the speed of the work has twelve changes, 
from 40 to 624 revolutions per minute. The speed at which the 
wheel rotates varies with the hardness of the work and the amount 
of stock to be removed at each cut. The traverse of the wheel 
should be greater for finishing cuts (which should always be light) 
than for roughing cuts. Wheels should be of such a grade that 
the dull particles will break away easily during the grinding 
operation; if the dull particles do not break away they become 
duller and collect metal, resulting in the glazing of the wheel 
which causes heating or chattering. A wheel that glazes rapidly 
is either too hard for the work it is performing, or it is running 
too fast. 

The harder the material to be ground, the softer should be 
the grade of the grinding wheel; for the harder material, dulling 
the wheel more rapidly necessitates a faster removal of the dulled 
particles. 



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GRINDING 273 

The speed at which the work rotates may be likened to the 
feed of the work in a milling machine, or the tool in a lathe; 
while the cutting points in the grinder wheel may be likened to 
the cutting edges. In other machines, if the work or tool be fed 
too fast, the resulting heat draws the temper of the cutting 
edges, which are rapidly dulled in consequence of the excessive 
feed; if fed too slowly, the cutter may be said to rub the work 
instead of taking a distinct chip — this also resulting in a rapid 
dulling of the cutting edges. 

If we rotate the work too fast, when the grinding wheel is 
running at the proper speed, there will be too much stress upon 
the cutting points, causing the work to chatter and which, by their 
breaking away, rapidly change the diameter of the wheel and 
consequently the diameter of the work. For this reason, too 
great a surface speed of the work rapidly destroys the sizing 
power of the wheel. 

The wheel will also dull rapidly in case we revolve the work 
too slowly, because there is not enough stress on the cutting 
points to break them. In ordinary practice, the peripheral speed 
of the grinding wheel ranges from 6,000 feet per minute for hard 
metals to 7,000 feet for soft ones. The average perimeter sp^d 
of the work is about 100 feet per minute. 

It is especially important that no change in the temperature 
of the work occur, as a change in temperature produces a resultant 
change in the axis, rendering it impossible to produce true work. 
To obviate this difficulty the work is flooded with water. 

1 145. Trial Settings. The graduations on a universal grinder, 
those on the table ends, the head-stock, the slide, and elsewhere 
secure approximate settings only, not because they are inaccurate, 
but because of changes in temperature and wear in the emery 
wheel, etc. The necessary trial settings should always be made 
as carefully as possible, but as soon as the entire surface becomes 
bright, the feeding should stop, the machine be allowed to operate 
until the sparking ceases, and then stopped for accurate measure- 
ments with the micrometer or gage. If the settings are inaccu- 
rate, others should be made and the process repeated until final 
correct settings are had. 

1146. Chattering. Chattering is caused if the grinding wheel 
is operating at the correct speed, by rotating the work too rapidly. 
Other common causes are looseness in the wheel spindle, lack of 



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274 ENGINEERING AND SHOP PRACTICE 

truth in the wheel, too wide a wheel face, inherent lack of stiffness 
in the work, and too hard a wheel. The following remedies are 
suggested: slender w^ork should be supported by the steady rest; 
adjustments should be carefully made and tested; the wheel 
should be trued if not round, replaced if too hard or too wide, 
although if too wide, it might be thinned down with the diamond; 
if the work be rotated too rapidly, it should be given a slower speed. 

1 147. Remarks and Reputable Practice. The following ex- 
tracts are taken from an article by Mr. Norton which appeared 
in the American Machinist: 

"The amount of work produced by grinding has increased with 
the increase of water, and now it is known that soda water in- 
creases the product from any given wheel; later the introduction 
of oil into the soda water has still further increavsed the effective- 
ness of wheels, and made the work of the operator pleasanter, 
on account of greater neatness. Recently the writer has used a 
so-called 'drilling compound' and found it excellent when suffi- 
cient soda is added to prevent rust. 

"All really good wheels will grind in either soda water, soapy 
water or oil. It is only necessary that they be graded rightly. 
The popular idea that oil must not be allowed to get near any 
grinding wheel is erroneous. It would be bad to soak some 
wheels in oil, or to allow oil to penetrate in spots; but no really 
good wheel to-day can be injured by flowing liquid oil on to the 
work or wheel while the wheel is revolving at a sufficient speed to 
accomplish its work; and some wheels may be soaked in oil 
indefinitely without the slightest injury. 

"Another erroneous impression, not, however, so common, is 
that emery adheres to ground surfaces, causing cutting of bearings, 
when used. It would seem clear to reason that should the emery 
adhere to the steel there could be no grinding, but instead the 
wheel w6uld be torn away. The fact is that neither the micro- 
scope nor chemical laboratory reveals an atom of carbon in any 
form adhering to the steel. 

"There still remain a few who suppose that copper, Babbitt, 
lead, and soft rubber cannot be ground with emery and corundum 
wheels because the material adheres to the cutting wheel; when, 
the fact is, there is no substance of which the writer has any 
knowledge that cannot be ground successfully with a wheel 
suitably constructed for each case." 



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GRINDING 275 

1 148. Order of Operations for Cylindrical and Conical Grind- 
ing. Observe the following order of procedure when operating 
the universal grinder: 

1. Adjust the vxyrk. Attach a special grinder dog to one end 
of the work, put a drop of oil in the center in each end, and place 
between the clean centers of the grinder, noting that no end play 
exists, i,e,y that the spring tension is in operation. When taper 
grinding, the table must be set by means of the adjusting screw. 
A setting is effected by traversing the emery wheel back and 
forth and noting the difference between the wheel and the work 
in the extreme position. In most instances these should be 
equal; in other words, the line of the wheel traverse should be 
parallel with the rough surface of the work. 

2. Adjust the emery wheel and traverse carriage. The emery 
wheel is brought into its proper relation with the work, and the 
screw dogs adjiLsted on the traverse wheel to give the desired 
length of the traverse; this latter adjustment may be effected by 
moving the traverse carriage back and forth with the traverse 
wheel by hand. Special precaution must be taken to see that 
the wheel does not collide with the dog or any projection on the 
work or chuck. 

3. Determine the speeds and traverse. Calculate the speeds 
and consult the table, Sec. 428, then adjust the belts to obtain 
them. 

4. Pull over by hand. With all adjustments made and the 
wheel and work in position, pull over by hand, and traverse 
the carriage to avoid breakage and to ascertain the accuracy of 
the adjastments. 

5. Adjust the water guards. Adjust the water guards and turn 
on the water. 

6. Start the grinder. With the work revolving and the running 
wheel at one end of its traverse, bring it slowly towards fhe work 
until it begins to cut. 

7. Throw^in the automatic traverse. By means of the automatic 
traverse knob and lever, throw in the automatic traverse, feeding 
the wheel only at the end of each cut. The work should be 
carefully watched to detect any irregularity in the w^orking of 
the machine. Be ready to take advantage of every opportunity 
to save time. 

8. Take measurements. As soon as the entire surface has 



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276 ENGINEERING AND SHOP PRACTICE 

become bright, stop feeding and allow the machine to operate 
until the wheel ceases to spark. Stop the machine and measure 
the diameter at each end with the micrometer calipers or gage; 
if the adjustment is incorrect, the table is readjusted and the 
operation is repeated; a few trials will probably be necessary 
before the exact adjustment is obtained. 

Note. To avoid the production of work that is too small it 
is necessary in sizing to use the utmost care both in grinding and 
in the taking of measurements. 

1 149. Lapping. Lapping is an abrasive process of refinement 
and bears the same relation to the finishing of ground work that 
scraping does to the finishing of planed work. A lap is com- 
posed of some soft metal such as lead, brass or cast iron, in which 
are imbedded the grains of the abrading material; in general; 
only the very finest numbers of flour emery are used. Where 
necessary that either the lap or the work be rotated at a high 
speed during the lapping process, this may be done in a speed 
lathe. It is essential, in order to secure a successful operation, 
that plenty of oil be supplied to the lap. 

Plane surfaces may be lapped in the following manner: the face 
of the lap, which is usually cast iron, is coated with oil and emery; 
the work is then rubbed over it, care being taken to change the 
direction of the rubbing frequently in order to prevent crowning. 

Abrasives and Abrasive Wheels 

1151. Carborundum — Scale of Hardness. Carborundum 
(carbide of silicon) SiC, is an artificial abrasive and is manu- 
factured in an electric furnace. In the following scale of minerals 
taken to represent the lOdegreesof hardness, talc ranking 1 and the 
diamond 10, carborundum will be found between the numbers 
9 and 10. (1) Talc (easily scratched with the finger nail) ; (2) Gyp- 
sum; (3) Calcite; (4) Fluorite; (5) Barite; (6) Feldspar; (7) Quartz; 
(8) Topaz; (9) Corundum or Sapphire (a form of crystallized co- 
rundum); (10) Diamond (the hardest substance known). 

1152. Alundum. Alundum, a recently developed abrasive, 
is produced, like carborundum, in an electric furnace at an 
extremely high temperature. Alundum is claimed by the manu- 
facturers, the Norton Emery Wheel Co., to be the hardest, sharpest, 
and most durable abrasive material known. The raw material, 
Beauxite, an amorphous hydrate of aluminum, is transformed 



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GRINDING 277 

at a temperature estimated between 6000 and 7000 degrees Fah- 
renheit, into alundum, a material resembling in chemical compo- 
sition the purest natural corundum. In the scale of hardness, 
where the diamond is 10, alundum has been found by trial to 
exceed 9J. 

1 153. Corundum. Corundum is pure alumina or oxide of 
aluminum, A1,0,. It is a natural mineral, crystalline in structure, 
and in the scale ranks next to the diamond in hardness. 

1154. Emery. Emery is a compound of corundum and 
protoxide of iron. Its hardness is about one degree lower than 
corundum, while the presence of iron renders the grains slightly 
tougher and less brittle. The most important emery mines are 
to be found in the northeastern portion of the United States. 

1155. Grindstones. Grindstones are natural sandstones of a 
suitable texture for grinding. The cutting material is quartz 
sand, oxide of silica, SiO,, the grains of which are bound together 
by a natural calcareous or silicate bond. The stone is quarried 
and turned into discs; these latter are the grindstones of commerce. 

1 156. Abrasive Wheels and Wheel Speeds. Commercial abra- 
sive wheels are manufactured from carborundum, alundum, co- 
rundum and emery by combining the cleaned and sorted grains 
of the cutting material with a suitable matrix or bond. The 
wheels are pressed into shape and are hardened by a process of 
drying or vitrification as the nature of the bond requires. It is 
essential in all abrasive wheels that the bond be of such a nature, 
whether natural or artificial, that it be soft enough to release the 
grains after their projecting comers have been worn; hard enough 
to retain the grains until these comers have done their work; 
and of such strength that the wheel will be capable of resisting 
the centrifugal force due to the speed at which such wheels must 
be run to secure the greatest efficiency. 

The table of abrasive wheel speeds (Fig. 1156) gives the 
number of revolutions per minute for specified diameters of wheels, 
to cause them to run at the respective periphery rates of 4000, 
5000, 6000 and 6500 feet per minute. A rate of 5000 feet is 
usually employed in ordinary work, but in special cases and 
where safety collars are used, it is sometimes desirable to run 
them at a higher or lower rate according to the requirements. 
The stress on the wheel at 4000 feet per minute is 43 pounds 
per square inch; at 5000 feet, 75 pounds; and at 6000 feet, 108 



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278 



ENGINEERING AND SHOP PRACTICE 



pounds. Wheels that are to be run wet, like tool-grinder wheels, 
are usually run at the lowest speed of 4000 feet per minute, as 
that is about as fast a speed as water can be kept on the sur- 
face of the wheel. Wheels with holes } to J their diameter are 
much weaker than solid wheels of the same size, and should not 
be run faster than 4000 feet. Tub or cup wheels, if not pro- 
tected in any manner, should be run between 3000 and 4000 feet 
per minute, while ring wheels in chucks may be run from 5000 
to 6000 feet per minute. 



Table of Abrasive Wheel Speeds 





SLOW 


ORDINARY 


MEDIUM 


MAXIMUM 




FOR WET AND CUP 


FOR GENERAL SHOP 


FOR WHEELS WITH 


FOR WHEELS WITH 




WHEELS 


PRACTICE 


SAFETY COLLAR 




Diameter 
Wheel 


Rev. per minute for 

surface speed of 

4,000 ft. 


Rev. per minute for 

surface speed of 

6,000 ft. 


Rev. per minute for 

surface speed of 

6,000 ft. 


Rev. per minute for 

surface speed of 

6.500 ft. 


1 inch 


15,279 


19,099 


22,918 


24,000 


2 " 


7,639 


9,549 


11,459 


13,000 


3 *' 


5,093 


6,366 


7,639 


8,670 


4 " 


3,820 


4,775 


5,730 


6,240 


5 " 


3,056 


3,820 


4,584 


5,200 


6 " 


2,546 


3,183 


3,820 


4,333 


7 *' 


2,183 


2,728 


3,274 


3,500 


8 " 


1,910 


2,387 


2,865 


3,100 


10 " 


1,528 


1,910 


2,292 


2,500 


12 " 


1,273 


1,592 


1,910 


2,050 


14 " 


1,091 


1,364 


1,637 


1,775 


16 " 


955 


1,194 


1,432 


1,550 


18 " 


849 


1,061 


1,273 


1,375 


20 " 


764 


955 • 


1,146 


1,250 


22 *' 


694 


868 


1,042 


1,125 


24 " 


637 


796 


955 


1,035 


26 " 


586 


733 


879 


950 


28 " 


546 


683 


819 


886 


30 " 


509 


637 


764 


825 


32 " 


477 


596 


716 


780 


34 " 


449 


561 


674 


728 


36 " 


424 


531 


637 


700 


38 " 


402 


503 


603 


655 


40 " 


382 


478 


573 


624 


42 " 


364 


455 


546 


600 


44 " 


347 


434 


521 


565 


46 " 


332 


415 


498 


541 


48 " 


318 


397 


477 


500 


50 '* 


306 


383 


459 


496 


52 " 


294 


369 


441 


478 


54 " 


283 


3,54 


425 


461 


56 •' 


273 


341 


410 


443 


58 " 


264 


330 


396 


428 


60 " 


255 


319 


383 


414 






Fio. 1156. 


_. _ 





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GRINDING 279 

1 157. Number of Grains and Character of Surface Cut by 
Them. The number or ffrain of a wheel refers to the size of the 
grains of which it is made. The grains are divided and numbered 
as follows, the numbers indicating the threads per lineal inch in 
the sieves through which they pass: 6, 8, 10, 12, 14, 16, 20, 24, 30, 
36, 40, 46, 50, 60, 70, 80, 90, 100, 120, 150, 180 and 220. 

The degree of smoothness of the surface which these num- 
bers leave may be roughly compared to that left by files, as 
follows: 

8 and 10 represent the cut of a wood rasp. 
16 and 20 represent the cut of a coarse rough file. 
24 and 30 represent the cut of an ordinary rough file. 
36 and 40 represent the cut of a bastard file. 
46 and 60 represent the cut of a second cut file. 
70 and 80 represent the cut of a smooth file. 
90 and 100 represent the cut of a superfine file. 
120 and finer represent the cut of a dead smooth file. 

1 158. Grade or Hardness. The grade of an abrasive wheel 
refers to its hardness, that is, the resistance of the particles to the 
pressure exerted in the act of grinding. A wheel whose particles 
are easily broken away from it is termed soft, while one from 
which the particles are not easily broken is hard. 

The Norton Emery Wheel Co. uses 26 grade marks, the Car- 
borundum Co. 19, while the Safety Emery Wheel Co. uses 40. 
The following table (Fig. 1158) is a comparison between the 
grade designations of the Norton Emery Wheel Co. and the 
Carborundum Co. Intermediate letters between the grade desig- 
nations indicate relative degrees of hardness between them. The 
Norton Emery Wheel Co. manufacturing four degrees of each 
designation, while the Carborundum Co. manufactures but 
three. 



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2S0 



ENGINEERING AND SHOP PRACTICE 



Norton Emery Wheel Co. 



Grade Designation 



D. 



E. 



G 



H. 



M. 



N. 



Extremely or 
Very Soft 



Soft 



Medium Soft 



Medium 



O 



Q Medium Hard 

R ! 

S 

T 

U Hard 

V 

W 

X 

Y 



Extremely or 
Z • Very Hard 



Carborundum Co. 



u 



Q 



o 



N 



.M 



K 



H 



G 



E 



D 



Fig. 1158. 

The Safety Emery Wheel Co.'s grade list is an arbitrary one 
with the following designations: 

C. Extra Soft H. Very Soft 

A. Soft M. Medium Soft 



P. Medium 

0. Hard 

E. Extra Hard 



I. Medium Hard 

N. Very Hard 

D. Special Extra Hard 



Intermediate figures between those designated as soft, medium 
soft, etc., indicate so many degrees harder or softer, e.^., AJ is 



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GRINDING 



281 



one degree harder than soft. Aj is three degrees harder than 
soft or one degree softer than medium soft. 

1 159. Favorite Numbers and Grades of Abrasive Wheels. In 
Fig. 1 1 59a, a table for the selection of grades, will be found a com- 
parison of the grading used by the Norton Emery Wheel Co. and 
that of the Carborundum Co. Fig. 11596 is the grading list used 
by the Safety Emery Wheel Co. 



Class of Work 



Large Cast Iron and Steel Castings 
Small Cast Iron and Steel Castings 
Large Malleable Iron Castings. . . 
Small Malleable Iron Castings . . . 

Chilled Iron Castings 

Wrought Iron 

Brass Castings 

Bronze Castings 

Rough Work in General 

G?neral Machine Shop Use 

Lathe and Planer Tools 

Small Tools 

Wood-working Tools 

Twist Drills (Hand Grinding) . . . 
Twist Drills (Special Machines) . . 
Reamers, Taps, Milling Cutters, 

etc. (Hand Grind) 

Reamers, Taps, Milling Cutters, 

etc. (Spec. Mach.) 

Edging and Jointing Agricultural 

Implements 

Grinding Plow Points 

Surfacing Plow Bodies 

Stove Mounting 

Finishing Edges of Stoves 

Drop Foldings 

Gumming and Sharpening Saws 
Planing Mill and Paper Cutting 

Knives 

Car Wheel Grinding 



Norton Emeey Wheel 



Number 

UsuaUy 

Furnished 



16 to 
20 to 
16 to 
20 to 
16 to 
16 to 
16 to 
16 to 
16 to 
30 to 
30 to 
36 to 
36 to 
36 to 
46 to 



20 
30 
20 
30 
20 
30 
30 
30 
30 
46 
46 
100 
60 
60 
60 



46 to 100 



46 to 60 



16 to 
16 to 
20 to 
20 to 
30 to 
20 to 
36 to 

30 to 
20 to 



30 
30 
30 
36 
46 
30 
60 

46 
30 



Grade 

Usually 

Furnished 



QtoR 
PtoQ 
QtoR 
PtoQ 
QtaR 
PtoQ 
OtoP 
P toQ 
PtoQ 
O toP 
NtoO 
NtoP 
MtoN 
MtoN 
KtoM 

NtoP 

HtoK 

QtoR 
PtoQ 
NtoO 
PtoQ 
O toP 
PtoQ 
MtoN 

J toK 
O toP 



Carborundum Co. 



Number 

Usually 

Furnished 



16 to 24 
20 to 30 
16 to 24 
20 to 30 
16 to 24 
16 to 24 
20 to 36 
20 to 30 
20 to 30 
24 to 36 
30 to 36 
50 to 80 
40 to 60 

60 

60 

50 to 80 
50 to 60 

141 to 24 
20 to 24 
16 to 20 
24 to 30 
24 to 30 
24 to 36 

403—603 



Grade 

Usually 

Furnished 



GtoH 
G toH 
G toH 
Hto I 

H 
FtoH 
Hto I 

I 

H 
G to J 
I to J 
I to J 
L toM 
I to J 
L toO 



KtoN 



L toM 



G to 
H 
G 
G 
G 
G to 
J to 



202— 60 to 80 MtoR 
16 to 24 I H 



Fig. 1159a. 



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282 



ENGINEERING AND SHOP PRACTICE 



The Grading used by the Safety Emery Wheel Co. of Springfield, 

Ohio 



Kind of Work 



Number 

Usually 

Furnished 



Grade 



Coarse Grinding 

Stove castings 

Agricultural castings (malleable and gray iron) . . . 

Small malleable castings 

Drop foiling fins 

Scale from soft steel forging 

Rough brass castings 

Roughing out lai^ machine-shop tools 

Rough surfacing on wrought iron 

Surfacing soft steel (coarse) 

Surfacing cast iron (coarse) 

Surfacing chilled iron (coarse) 

fkiging shovels 

Steel plow jointing 

Jointing and edging agricultural implements 

Thin edges of hoUow-ware 

ChiUed car-wheel grinding 

Cast-iron cai^wheel grinding 

Grinding car-wheel tires (steel) 

Edges of wrought-iron butts and hinges 

Rough grinding on malleable car couplings 

Grinding edges of cast-iron radiators 

Grinding wood pulp 

Rough surfacing on sad irons 

Grinding ends of iron or steel rods 

Jointing wrought-iron bridge work 

Surfacing cast-iron mold boards 

Bronze casting 

Rough machine-shop use 

Edging sheet steel 

Wrought-iron wagon work 

Grinding ends of carriage axles 

Internal grinding (roughing out) 

Surface work on dies 

Surface work on carriage axles 

Safe work 

Edging sad irons 

Medium Grinding and Coarse Tool Work 
Saddlery hardware castings (malleable) 



20 to 30 
16 to 20 
24 to 36 
20 to 30 
20 to 30 
20 to 24 
24 to 30 
16 to 24 
20 to 30 
16 to 30 
20 to 30 
20 to 30 
20 to 24 
20 to 30 
20 to 30 
16 to 20 
16 to 24 
20 to 30 
20 to 30 
14 to 20 

20 

20 
20 to 30 
20 to 30 
16 to 20 
20 to 36 
20 to 30 
20 to 30 
30 to 36 
20 to 36 
20 to 36 
24 to 46 
20 to 46 
20 to 36 
16 to 20 

20 



24 to 36 



I }to01 
I itoO} 
O JtoN 
O toN 
toO 1 
ftoOi 
tol i 
i toO 
itoOi 

toO 
JtoO i 
toO| 
itoO 
tol i 
toNi 
itol } 
itol } 
Itol } 
toOi 
O JtoN 

toO i 
N 

1 ItoO 

i toE 
OitoO} 

1 itoO 

toO} 

1 i to O i 
I ItoOi 
O i to O i 

toO } 

1 itoO i 
Mi to I 

I JtoO 
P ItoO 
O toOi 



N orE 



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GRINDING 



283 



Grading Used bt Safety Emebt Wheel Co. {andinued). 



Kind of Work 



Namber 
UsuaHy 
Furnished 



Gnde 



Medium Grixdino and Coarse Tool Work — 
Continued 

Surface brass (ooaise) 

Surfacing tempered steel (coarse) 

Grinding cast-steel hanuneis 

Jointings edges of sheet-iron or steel 

Surtscing chiUed-iron plows 

Stove mounting 

Polishing edges of stoves 

Sharpening lawn mowers 

Pointing and sharpening guards 

Sharpening mower and reaper knives 

Water tool grinding 

Twist drill grinding 

General machinenshop use 

Shaping Mushet steel tools 

Sharpening large machine-shop tools 

Grinding inside of cast-iron hollow-ware 

Grinding inside of stamped hollow-ware 

Finishing the heads of machine screws and bolts . . 

Gumming and sharpening saws 

Planing-mill tools, molding cutters, etc 

Planing-mill and paper-cutting knives 

Lathe and planer tools 

Edging files 

Ends of wagon springs 

Surfacing faces of pulleys 

Grinding out boiler holes in stove tops and centers 

Small malleable or gray-iron castings 

Bottoms and edges of iron shoe lasts 

Grinding shear knives 

Surfachig sides of circular saws 

Rim bands on carriage hubs 

Brass car boxes 

Grinding ends of spiral springs 

Leveling oflF rivet heads 



Fine Grinding and Tool Finishing 



Universal grinding machine 

Sharpening small machine-shop tools 



30 to 
36 to 
30 to 
20 to 
20 to 
24 to 
36 to 
36 to 
24 to 
46 to 
30 to 
46 to 
24 to 
30 to 
24 to 
30 to 
36 to 
36 to 
46 to 
46 to 
36 to 
30 to 
30 to 
30 to 
30 to 
30 to 
24 to 
30 
30 to 
36 to 
36 to 
30 to 
46 to 
30 to 



36 
46 
36 
36 
30 
36 
46 
60 
36 
60 
46 
60 
36 
36 
36 
46 
46 
46 
60 
60 
60 
46 
60 
46 
36 
46 
36 

36 
60 
46 
36 
60 
36 



60 to 100 
60to 80 



i 



i 



P to Pi 
M toP 
I itol ) 
I itoOi 
I itoOi 
O ito N 
O toOi 

tol i 

toO i 

tol i 

tol 
ItoP 

tol 

tol 

tol 
}toI 

f 

P itol 
A itoMi 
M 

to A i 
tol 
tol f 
toO i 
tol i 

ftoNi 

1 }toO 
i toO 
itoM 
i toM 

toO 
i toO i 
ftoO i 
itoO 



A 
P 

I 
O 
I 



I 
A 
A 
I 
I 
I 
I 



A i to M 
M to P J 



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284 



ENGINEERING AND SHOP PRACTICE 



Grading Used by Safety Emery Wheel Co. (contintied). 



Kbd of Work 



Fine Grinding and Tool Finishing — 
Continued 

Sharpening reamers and taps 

Sharpening milling cutters 

Grinding chilled rolls 

Finishing chilled rolls 

Grinding pearl 

Grinding leather splitting knives 

Brass finishing 

Dental and surgical instniments 

Grinding and concaving razors 

Grinding shoe knives 

Fine hardened steel tools 

German silver 

Shoe cutting dies 

Ends of steel wire 

Internal grinding (finishing) 

Grinding lathe centers 



Number 

UsuaUy 

Furnished 



60 to 100 
60 to 100 
36 to 46 
60 to 100 
46 to 100 

90 
60 to 100 
46 to 100 
70 to 100 
70 to 90 
80 to 120 
80 to 120 
60 to 80 
70 to 90 
60 to 100 
60to 80 



Grade 



A 1 to M i 
A }toMi 
A itoMi 
A itoM 
Af 
AJ 
M 

M toP i 
A JtoM 
P itol 
A } to M i 
M toP 
P to I 
P itol i 
M toMi 
M 



Fig. 11596. 



To get a fine finish use the finer numbers and soft grades. 
For fast work the coarse numbers and hard grades. 



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CHAPTER XII 

PLANING 

Planing Machines 

12 1 1. Classes of Planing Machines. There are three distinct 
classes of planing machines in common use, viz.: the shaper for 
light work; the slotter for finishing flat or curved surfaces, at 
right angles to some other surface of the work, and the planer for 
heavy work. There are several varieties of each of these classes, 
the design of each class varying according to the ideas of the 
manufacturer, and the work for which the machine is intended. 

Shapers are usually crank or gear driven, while planers are 
spur or spiral-geared, the adjectives having reference to the method 
of driving the platen. 

The Shaper 

122 1. Function and Limitations. The function of the shaper, 
like that of the planer, is to produce flat surfaces. It is designed 
for light work, and work of such character as may be held in a 
vise, with which it is usually equipped. In contrast with the 
planer, the tool moves over the work instead of the work under 
the tool. In the planer the tool is fed sidewise during the return 
stroke of the work, while in the shaper the work feeds sidewise 
during the return stroke of the tool. In this machine the head is 
fastened to one end of a reciprocating ram, which causes the tool 
to be moved back and forth horizontally over the surface of the 
work. The carriage, to which the vise and work are fastened, is 
so arranged as to move sidewise a distance equal to the width of 
the cut, while the tool is performing the return stroke. 



285 



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286 ENGINEERING AND SHOP PRACTICE 



Fig. 1221. — Hendey Geared Shaper. 



1222. Description. A standard type of the modem crank 
shaper consists of a body or column which supports the driving 
mechanism, the vise and various stationary and movable parts 
of the machine; a longitudinally movable raniy at the end of 
which is fastened the heady slide y tool-box and tool-post; the column 



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PLANING 287 

also supports the movable table to which the vise or work is 
fastened. The ram slides in flat or dove-tailed bearings formed 
on the top of the column; at its front end it carries the shaper- 
head and slide which gives the down feed; this head is always so 
arranged that it can be adjusted in such a manner as to make 
any angle with the top surface of the table; it is provided with 



Fig. 1222. — Gould & Eberhardt High-duty Crank Shaper. 

suitable locking arrangements. The driving mechanism, by means 
of which the ram is moved to and fro over the work, is operated 
by a cone pulley through back gears, a crank and slotted lever. 
The length of the stroke and the position of the ram are adjustable 
with reference to the work. The table is fastened by bolts to a 
saddle which is gibbed to a cross-rail and can be moved along it 
in either direction, automatically or by hand. The cross-rail, 
which is attached to the face of the column, may be raised or 
lowered by means of screw and miter gears, or clamped to the 



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288 ENGINEERING AND SHOP PRACTICE 

column at any desired height. The table which carries the mov- 
able vise is T-slotted, so that large work may be bolted to it. 
The driving mechanism, enclosed in the column, consists of a 
forked block clamped in a slot in the ram by means of a handle; 
a heavy slotted lever is fastened at its lower end to the column, its 
upper end engaging the forked block. This lever is moved back 
and forth by means of a crank-pin which is carried on the large 
gear; this gear is driven, either by a pinion keyed on the same shaft 
with the cone pulley, or through back gears. As this gear re- 
volves, the crank-pin which carries the block sliding in the lever 
causes the lever to move back and forth. It is obvious that if we 
alter the distance from the center of the crank-pin to the center 
of the gear carrying it, we produce a corresponding change in 
the stroke of the ram. This is accomplished by having the 
crank-pin attached to a quadrant which can be rotated about a 
center near the rim of the gear; the quadrant is moved by means 
of a rack and pinion; this pinion is so arranged that it may be 
operated by hand; when the quadrant is in the desired position 
it may be clamped there. 

1223. Characteristic Operations. It is important to under- 
stand the following operations and adjustments of the shaper 
before starting to work: 

1. The correct method of setting the tool, and the adjustment 
of the tool-box so as to give the necessary relief to the tool on the 
retjim stroke. 

2. The quick return motion by means of which the movement 
of the ram is controlled. 

3. The adjustment of the back gears to secure the proper 
cutting speed. 

4. The device for regulating the length of the stroke. 

5. The device for regulating the position of the stroke. 

6. The method of raising or lowering the cross-rail and the 
movement of the table. 

7. The method of adjusting the automatic feed mechanism; 
how to obtain a desired width of cut. 

8. The method of reversing the direction of the feed and how 
to throw it into or out of action. 

9. The method of adjusting so as to make the feeding take 
place during the return stroke. 



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PLANING 289 

Slotters and Key-way Cutters 

1231. Description of Slotting Machines. The slotting ma- 
chine is a modification of the shaper, and might in fact be termed 
a vertical one, as the action of the ram is vertical. A common 



Fig. 1231. — Belts Slotting Machine. 

type of slotting machine consists of the following essential details: 
A rigid frame carrying the ram and its driving mechanism, the 
carriage and platen, with its automatic feed mechanism; a vertical 
ram, situated directly above the platen, carries the tool; a cir- 
cular platen, mounted on a carriage similar to a lathe carriage, 
is provided with rotary, automatic, longitudinal and cross feeds. 

Power is transmitted through a cone pulley and back gears to 
a crank on the driving shaft, situated back of the ram. The 



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290 ENGINEERING AND SHOP PRACTICE 

rotary motion of the crank is transformed into a reciprocating 
motion of the ram through adjustable crank and wrist pins and 
a connecting rod; the ram is counterbalanced and provided with 
both vertical and horizontal tool clamps. 

1232. Slotter Tools. Slotter tools that are used with their 
shanks in a vertical position are essentially different in shape 
from either the ordinary planer or shaper tools in that the cut- 
ting edge is formed at the end of the bar. They resemble to 
some extent a parting tool, with the exception that the end face 
turns the chip. See Sec. 455. 

1233. Key-way Cutters. A key-way cutter may be defined 
as a vertical draw-cut shaper, the draw-cut shaper being one de- 
signed to cut on what would be the return stroke of the ordinary 
shaper. As the name implies, this form of slotter is designed 
primarily for the cutting of key-ways in the hubs of pulleys, 
gears and similar work. 

The Planer 

1241. Function and Limitations. The function of the planer 
is to produce a fiat surface; this is accomplished by fastening the 
work to a movable platen which is made to reciprocate horizon- 
tally beneath the tool, the latter being moved after each forward 



Fig. 1241a. — Whitcomb 2%" Belt Drive, Belt-driven Planer. 



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PLANING 291 

stroke of the platen a distance equal to the width of the cut. 
The tool is fed across the work at right angles to the line of 
motion of the platen or table. Planers are designed for heavy 
work, and are generally made to run at a fixed rate of speed — 
about 24 feet per minute on the cutting stroke; the return stroke 
is, for obvious reasons, so arranged as to occupy less time than 
the cutting stroke. That the high-speed tool steels may be used 



Fio. 12416. — Gray 30* Spiral-geared Planer. 

to advantage many planers are designed with a speed far in 
excess of the 24 feet mentioned, 40 feet or more being common. 
Some electrically driven planers have a variable speed control 
which will give speeds of 90 feet and 100 feet per minute. 

1242. Description. A standard type of the modem planer 
consists of a platen or table ^ which slides in V-shaped or flat 
guides on the top of the bed. Heavy housings are securely bolted 
to the bed, the movable cross-rail being bolted to the front facings 
of the housings. This cross-rail carries the saddle to which is 
attached the planer head. This head is equipped with a slide 
operated by the doum-feed handle; bolted to this slide is the tool- 
box for holding the tools. The saddle is moved along the cross-rail 
by means of a feed screw, operated automatically or by hand as 
desired; likewise, the slide is operated either automatically or by 



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292 ENGINEERING AND SHOP PRACTICE 

hand by means of a feed rod. The platen is reciprocated by 
means of gearing connected to driving and reversing pidleys. 
The length of the stroke and the direction in which the platen 
moves are governed by adjustable tappets or dogs which engage 
a reversing lever connected in turn to belt-shifting levers. Screws 
within the housings are used to raise and lower the cross-rail. 



Fig. 1242. — Cincinnati 36* Spur-geared Motor-driven Planer. 

These screws are made to operate simultaneously by means of 
bevel gears. 

1243. Characteristic Operations. It is important to under- 
stand the following operations and adjustments of the planer 
before starting to work : 

1. The method of raising and lowering the cross-rail, and 
the adjustments of the slide; these should be close to the work 
to avoid the springing of the tool. 

2. The correct method of setting the tool, and the adjustments 
of the tool-box so as to give the tools the necessary relief on the 
return stroke. 

3. The adjustment of the tappets or dogs to give the required 
length of stroke. 



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PLANING 293 

4. The method of stopping the platen or table and starting 
it in either direction without stopping the machine. Caution. 
This method should only be resorted to in cases of accident or 
emergency. Always stop this, or any other machine for taking 
the measurements, or when it is necessary to leave the machine, 
if only for a moment. 

5. The method of adjusting the automatic feed mechanism; 
how to obtain a desired width of cut. 

6. How to instantly throw the horizontal or vertical feed into 
or out of action. 

Planing 

1251. Preparatioii of Work. Prior to fastening planer work in 
the vise or to the platen it should be laid out to the drawing in 
accordance with the instructions given under the subject ** Laying 
Out," Sec. 711, in Chapter VII. After the preparatory process of 
laying out the work, a suitable method of fastening the work or 
piece for the planing operation should be selected. If the work 
be large it may be fastened in some of the following ways: it may 
be bolted directly to the platen; it may be fastened by means of 
"U-" clamps and bolts; or it may be secured by means of planer 
pins and toe dogs, or a combination of these methods. When 
clamping work it is important that the points of clamp pressure 
be located directly over the points of support and that the work 
be securely backed up and fastened to prevent subsequent slip- 
page. Leveling wedges, planer jacks and various other devices are 
used to effect a workmanlike job of fastening. The surface gage 
is used in bringing lines or surfaces parallel with the table. When 
the line on the work is to be set parallel with the line of motion 
of the table, it may sometimes be necessary to place the surface 
gage at some convenient position on the slide, or in the position 
of the tool; and then move the table and the work under the 
cross-rail. The movement then of the platen and work under 
the cross-rail will indicate at the scriber point the condition of 
the setting. Work that is not too far from the edge of the platen 
may be calipered from the line to a straight-edge placed against 
the side of the platen. 

Light, small work of convenient shape is generally held in a 
vise. Whether held in a vise or not the work should be so placed 
that the tool will travel lengthwise over its largest surface. If 



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294 ENGINEERING AND SHOP PRACTICE 

the work is too thin to project above the jaws of the vise, parallel 
blocks of sufficient thickness are used. While tightening the vise 
the work should be struck lightly with the copper hammer to 
keep it firmly seated. 

1252. Cutting Speeds. The cutting speed of planer tools is 
governed by the same laws that govern the cutting speed of tools 
in general, and should vary not only with the character and 
texture of the metal, but also with the kind of cut. With the 
planer, which is designed and speeded for taking very heavy 
cuts on hard material, after the cutting speed has once been 
determined, it cannot be altered, unless some variable speed 
device is provided. The fixed rate of speed at which planers 
operate, except those for high-speed steels, is about 24 feet per 
minute, which, though making it an admirable tool for heavy 
cuts on hard material, puts it at a disadvantage for light cuts 
and such soft material as brass. The crank shaper, however, is 
provided with cone pulleys and back gears, which, with the 
adjustable stroke, provide a suitable range of cutting speeds. 
With the belt on any particular step of the cone, the ram makes 
a constant number of strokes per minute, whether the strokes 
be 1 inch or 1 foot in length. If the stroke be 1 foot long and 
the number of revolutions 60 per minute, we have one stroke 
forward and one stroke backward of the ram, for each revolution, 
w^hich gives in a 2 to 1 quick return shaper a varying cutting 
speed approximating 90 feet per minute. With the other condi- 
tions unaltered, if the stroke be shortened to 2 inches, we have 
the ram moving 2 inches forward and 2 inches backward, occupy- 
ing the same time as the previous operation and securing a cutting 
speed of but 15 feet per minute. 

Owing to the construction of the shaper and the lack of 
rigidity in the work, tool and ram, the cutting speeds for planing 
operations will be found somewhat lower than those for turning, 
milling and drilling. For this and other reasons the cutting speed 
for planing is about i that for turning operations. The work- 
man is advised to consult the table and chart in Sees. 424 and 429, 
chapter IV on " Cutting Tools, " for further information on this 
subject. 

1253. Planing Practice — Roughing and Finishing — Side and 
Down Cuts. Surfaces to be planed are usually finished in two 
cuts, one heavy roughing cut and one light finishing cut. Fin- 



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PLANING 295 

ishing cuts are generally between ^'^ and j^j^^ in depth. When 
more than one roughing cut is necessary, they should be as heavy 
as the tool and machine will permit. 

Side or down cuts may be made with a properly shaped tool 
by feeding it down over the sides of the work. For a vertical 
surface the head should be set at degrees, with the top of the 
tool-box swung away from the work about 10°. 

1254. Planing Recesses and Grooves. In planing recesses 
or wide grooves cuts should be taken to the desired depth with a 
parting tool and the remainder of the stock worked out with a 
diamond-point or round-nose tool. 

1255. Planing Bevels or Angles. When cutting bevels or 
angles, such as V-ways or dove-tailed grooves, swing the head to 
the desired angle and proceed as in taking a vertical cut. 

1256. Under Cuts and T-Slots. When making an under cut 
or when cutting T-slots, a special tool is necessary. The tool 
should be blocked by placing a piece of wood between the shank 
and the head. W^here the shank of the tool is short a hinge- 
shaped device may be attached to its back in such a manner as 
to lift it clear of the work on the return stroke. These precau- 
tions are taken to prevent mishaps caused by the tool catching 
in the work. In work of this character the feeding is generally 
done by hand. 

As before intimated, planer cuts should always be taken 
lengthwise of the work when possible, i.e., in the longest direction 
of the surface. 

1257. Cuts Terminating in a Shoulder. For cutting key-ways, 
slots and cuts terminating in a shoulder, the crank shaper pos- 
sesses qualities of superiority over the planer, in that the stroke 
can be more readily adjusted, and when once set will be of exactly 
the same length each time. Owing to the slip of the belts, and 
for other reasons, this is not the case with the planer. 

A notch with a chisel or hole must be made for cuts that termi- 
nate in a shoulder, so that the tool may run out of the cut each 
time. This notch or hole — which in many cases should have been 
cored out — must be kept free of chips to avoid breaking the tool. 

1258. Accuracy and Errors. Owing to the rigidity of the 
planer, its work is more accurate than that of the shaper. In 
the shaper lack of rigidity in the ram and of support to the table 
causes undesirable spring of both ram and work, especially in 



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296 ENGINEERING AND SHOP PRACTICE 

long pieces. These errors are augmented by any looseness in the 
gibs and clamping bolts. 

1259. Order of Operations for Shaper. Observe the following 
order of procedure when operating the shaper: 

1. Place the work. Place the work in the vise so that the 
tool will travel lengthwise over its largest surface, slip underneath 
it parallel blocks of sufficient thickness to raise the surface a 
little above the jaws of the vise. While tightening the vise the 
work should be struck lightly with the copper hammer, to keep 
it firmly seated on the blocks. 

2. Adjust the table. Bring the cross-rail to the proper height, 
move the table over until the work is in its proper relation with 
the tool — the tool must just extend over one edge of the surface 
to be planed — and clamp the cross-rail. 

3. Adjust the tool. See that the tool is sharp and properly 
ground, then adjust and fasten it in the tool-post. 

4. Adjust the tool-box. Set the tool-box over about 10® — 
not the head; the top of the box away from the work — to obtain 
the necessary relief on the return stroke. 

5. Adjust the stroke. Loosen the knob locking the quadrant 
in position; with the crank handle on the pinion shaft through 
the knob, move the pointer to the desired stroke and tighten the 
knob. Pull over to determine the position of the stroke; if in- 
correct loosen the handle on top of the ram, and push forward 
or back until correct, then tighten the handle. 

6. Determine the cutting speed. Calculate it for the piece in 
hand and then adjust the belt and back gears to secure this 
speed. Consult the paragraphs on cutting speeds for planing 
operations. Sees. 424 and 429. 

7. Adjust the feed. Adjust the feed mechanism — generally 
coarse for roughing, and fine for finishing cuts; where accuracy 
may be sacrificed to speed, a coarse feed may be used for finishing 
— taking care that the feed movement occurs during the return 
stroke. Down feeding must generally be done by hand. 

8. Pull over by hand. With all the adjustments made, and 
the tool in its position over one edge of the work, pull over by 
hand to ascertain their correctness. 

9. Start the nmchine. Depth of cut. Start the machine and feed 
the tool down by hand until the desired depth of cut is obtained. 

10. Throw in the feed. Throw in the automatic feed and 



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PLANING 297 

watch the work carefully to detect any irregularity in the working 
of the machine. Be ready to take advantage of every opportunity 
to save time. 

1259^. Order of Operations for Planer. Observe the following 
order of procedure when operating the planer: 

1. Adjust the work. If the work be large, it may be fastened 
— always securely — in some one of the following ways to the 
platen: It may be bolted directly to the platen; or, it may be 
fastened by means of U-clamps and bolts; or it may be secured 
by means of planer pins and toe dogs or a combination of these 
methods. If the work be small and of convenient shape, it may 
be held in a planer vise; place the work in the vise so that the 
tool will travel lengthwise over its largest surface, slip underneath 
it parallel blocks of sufficient thickness to raise the surface a 
little above the jaws of the vise. While tightening the vise, as 
already noted, the work should be struck lightly with the copper 
hammer, to keep it firmly seated on the blocks. 

2. Adjust the tool. See that the tool is sharp and properly 
ground, then adjust and fasten it in the tool-box. 

3. Adjust the tool-box. Set the tool-box over about 10® — 
the top of the box away from the work — to obtain the necessary 
relief on the return stroke. 

4. Set the cross-rail and saddle. Bring the cross-rail and 
saddle into their proper relation with the work; the tool just 
over one edge of the surface to be planed. 

5. Adjust for travel. Set the tappets or dogs to give the 
desired length of stroke; this should be about Y longer than the 
cut. In the extreme forward position give about \'' over travel. 

6. Adjust the feed. Adjust the feed mechanism — coarse or 
fine as the work in hand demands — taking care that the feed 
movement occurs during the return stroke. 

7. Pull over by hand. With all of the adjustments made and 
the tool in its position over one edge of the work, pull over by 
hand to ascertain their correctness. 

8. Start the machine. Start the machine and feed the tool 
down by hand until the desired depth of cut is obtained. 

9. Throw in the feed. Throw in the automatic feed and watch 
the work carefully to detect any irregularity in the working of 
the machine. Be ready to take advantage of every opportunity 
to save time. 



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CHAPTER XIII 

MILLING 
Milling Machines 

131 1. Ordinary Types. Any machine that, while holding the 
work, operates upon it with a revolving cutter or mill, may be 
termed a milling machine. The three common types of milling 
machines are the plain, the vertical and the universal. 

13 12. Plain Milling Machines. Plain milling machines are 
designed for finishing surfaces that may be fed to the cutter in 
a straight line. They are usually arranged so that the work may 
be fed to the tool vertically and in two horizontal directions at 
right angles to each other. In this type of machine the spindle 
and the axis of rotation of the cutter are generally horizontal. 

13 13. Vertical Milling Machines. Vertical milling machines 
are so designated because the spindle and the axis of rotation of 
the cutter are vertical. Such machines usually have, in addition 
to the vertical and two horizontal feeds of the plain milling 
machine, a method of revolving the work in a horizontal plane 
for finishing circular surfaces. 

13 14. Horizontal Milling Machines and Rotary Planers. 
Horizontal milling machines are generally built for heavy straight 
work and resemble in a way the conventional planer with its 
deep bed and long platen or table and its characteristic housings; 
however, these machines partake of the ideas of their originators 
and to that extent are made in widely varying shapes and de- 
signs, according to the class of work they are to perform. These 
machines generally have two, three or four spindles, each of 
which carries its own mill and is independent in adjustment. 
As the construction would indicate, in most instances the table 
and work are movable in one direction only, the mills operating 
simultaneously on the several surfaces of the work. In a typical 
machine the table has a quick power movement of 20 feet per 
minute and is equipped with power feeds of from V to 12'' in 
either direction, per minute. 

298 



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MILLING 299 



FiQ. 1312. — Cincinnati Plain Milling Machine. 



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300 ENGINEERING AND SHOP PRACTICE 



Fig. 1313. — Brown & Sharpe Vertical Milling Machine. 



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MILLING 



301 



Fig. 1314a. — Ingersoll Four-head Horizontal Milling Machine. 

The rotary planing machines on the market are, according to 
definition, nothing more or less than a type of horizontal milling 
machine. The deep, rigid bed, instead of carrying the table, 
carries the cutter head — an inserted tooth mill — and its opera- 



FiG. 13146. — Newton Rotary Planer, Motor-driven. 

ting mechanism. The work is generally stationary, while the 
cutter head, which is often very large (84'' in diameter) is moved 
over the surface operated upon. 



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302 ENGINEERING AND SHOP PRACTICE 

13 15. Universal Milling Machines. Universal milling ma- 
chines are generally equipped with such a variety of attachments 
that they can be used for almost every conceivable milling opera- 
tion within the capacity of the machine. An indexing or universal 
dividing head is always furnished with the universal machines. 

The Universal Miller and Attachments 

1321. Ftmctions and Limitations. As has been stated, uni- 
versal milling machines are generally equipped with such a 
variety of attachments that they can be used for almost every 
conceivable milling operation within the capacity of the machine. 
A special attachment makes it possible to rotate the work while 
it is being fed longitudinally in a horizontal direction, thus pro- 
ducing helical or spiral work. The horizontal feeds, in addition 
to working at right angles to each other, can be made to operate 
at any desired angle within the limits of the machine. The table 
may sometimes be completely revolved through 360 degrees. 

Regarding limitations and errors, it may be stated that with 
the use of a sharp cutter and a high-grade milling machine opera- 
ting under favorable conditions, work may be turned out with the 
small limit of variation of one one-thousandth of an inch. The 
usual limit which obtains in the ordinary milling practice for 
such rough work as the square ends of reamers and taps and 
the faces of bolt heads and nuts is about four one-thousandths 
of an inch, and for a finer class of work, such as the various parts 
of fire arms, sewing machines and typewriters, the parts are 
finished within a limit of variation of two one-thousandths of an 
inch. 

1322. Description of Parts. An advanced type of universal 
milling machine — the Cincinnati — has the following construction 
and parts: A frame or column that supports the machine, the in- 
side of which is often used as a closet. The spindle for rotating 
the cutter arbor is hollow and has at its front end a Brown & Sharpe 
taper hole; this end of the spindle is also threaded to receive a uni- 
versal chuck. The spindle carries a cone pulley which receives its 
motion from a similar cone on a double-speed countershaft. Many 
machines are equipped with back gears, operated similarly to those 
of the ordinary lathe, for increasing the number of speed changes. 
The universal chuck provided, fits both the spindle and the 
dividing head and may be used on the spindle for holding straight- 



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MILLING 303 

shank reamers, drills, boring bars and special cutters. The over- 
hanging arm, which may be swung out of the way for end milling, 
supports the outer end of the cutter arbor with a bearing; this 
bearing is so constructed as to admit of being concentrically 
closed in as wear takes place. The main frame is of box form 
with its face side planed to receive the knee^ which slides upon it 
vertically, being raised or lowered by a screw operated by a pinion 



Fig. 1322. — Hciidcy-Norton Universal Milling Machine. 



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304 ENGINEERING AND SHOP PRACTICE 

shaft, which has on the outer end a detachable clutch handle. 
The saddle is placed on top of the knee and is operated by the 
transverse screw in a line parallel to the axis of the main spindle. 
The swivel carriage — circular in form — on top of the saddle, 
provides a substantial support for the table at whatever angle it 
may be placed; this swivel member is firmly bolted to the saddle 
by means of easily accessible "T"-head bolts. The power for 
driving the table is obtained from a small cone pulley on the 
rear end of the main spindle. For the slower feeds, this pulley 
is clutched directly to the spindle; and for the faster feeds runs 
loose on the spindle. While loose on the spindle this cone is 
driven by a gear arrangement which increases the rate of feed 
between two and three times. For this heavier duty of rapid 
feeding a higher belt speed is obtained. By raising the hand 
lever these gears are thrown out and at the same time the clutch 
on the small cone pulley is engaged with the clutch on the end of 
the spindle, or vice versa. Eight changes of feed, varying from 
.004'' to .OTO'^ travel of the table to one revolution of the cutter 
are provided, while a plate near the feed mechanism lever indicates 
the rate at which the machine is feeding. 

The rapid introduction of high-speed steel cutters has rendered 
imperative higher and more powerful feed mechanism and most 
milling machines are now equipped with positive feed devices. 
On the machine being described the positive feed mechanism 
consists essentially of two parts, an upper gear box at the rear 
end of the spindle and a lower gear box at the rear of the column. 
These two are connected by means of a vertically inclined shaft. 
Two speeds are imparted to this shaft for every speed of the 
spindle by means of a sliding gear in the upper box. This shaft 
in turn drives two feed gears in the lower gear box. These feed 
gears drive the two nests of cone gears which run loose on their 
shaft, independent of one another; the larger feed gear engaging 
the smallest gear on one cone and the smaller feed gear engaging 
the largest gear on the other cone, thus imparting widely different 
speeds to the two cones. From these cones, motion is trans- 
mitted to the various feed screws, through an intermediate gear, 
which is made to slide on the shaft by means of a rack and sector, 
and placed into correct position for engaging any one of the cone 
gears by means of the lever which actuates the sector. The 
position of this lever, at any time, indicates the rate at which 



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MILUNG . 305 

the machine is feeding, in thousandths of an inch, per revolution 
of the spindle, by means of raised figures on the lever qtmdrant. 
On a No. 1§ Universal Machine there are 12 feed changes: .005, 
.008, .011, .016, .023, .030, .042, .063, .095, .136, .190 and .253 
inch per revolution of the spindle. 

The lower lever having been placed in position, to obtain the 
desired rate of feed, the intermediate gear is brought into mesh 
with the proper cone gear by the upper lever (on lower gear box), 
which moves the entire lower portion of this mechanism. This 
is accomplished by means of a helical groove in the hub of the 
lever which engages a pin in the slide, upon which are mounted 
the lower lever, sector, rack and intermediate gear. It is evident 
that this mechanism makes possible a large number of feed 
speeds and that the changes to secure a given feed can be made 
in the short space of time required to shift the levers. 

The motion is transmitted from the lower small feed cone, or 
the lower gear box, by means of a universal jointed, telescope 
shaft to the stem gear which has its bearing in the back of the knee, 
and thence through a splined shaft to the cross- feed screw. The 
direction of the power fesd is changed by operating the tumbler 
gear through the crank. The operation of the automatic power 
cross-feed is as follows: the splined shaft has a clutch pinned to 
its outer end for engaging another clutch attached to a pinion 
operating the feed screw. The cross-feed is operated by a hand 
lever and may be thrown out automatically by means of trip 
dogs; it may also be operated by hand. 

The motion for feeding the table is imparted from the same 
splined shaft as that operating the cross-feed screw. Sliding on 
it is a bevel gear which transmits its motion through a vertical 
shaft, a pinion and gear to another vertical shaft centrally located 
within the carriage. On the upper end of this shaft a bevel 
gear meshes with a companion gear on the lead screw. This 
gear is journaled in the carriage and has clutch teeth for engaging 
a feathered clutch, sliding on and operating the lead screw. The 
hand-lever engages and disengages this clutch for starting and 
stopping the automatic table feed. On the front of the table, in 
" T " slots, wedge-surfaced trip dogs are provided for automatically 
disengaging this feathered clutch. Two handles, one at each 
end of the table, are provided for feeding by hand. The handle 
on the left end of the table is used for fine feeding; the one on the 



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306 ENGINEERING AND SHOP PRACTICE 

right end, a clutch crank, is used for rapid feeding and quick 
return. This clutch crank is also used on the shaft controlling 
the vertical motion of the knee. All adjustmerUs, indicated on 
the dialSy are in thousandths of an inch. 

1323. The Universal Dividing Head. The universal dividing 
head finds its greatest use in the division of the circumference of 
cylindrical work into a large range of equal parts. It is also 
used for helical (spiral) work, such as twist drills, spiral teeth on 
cylindrical and conical milling cutters; also the teeth of spiral, spur 
and bevel gears. 

Note, It is to be deplored that the words helix and spiral 
are synonymous terms to many mechanics. Grooves and gear 
teeth, that are in reality helical, are erroneously termed spiral. 
In accordance with the mathematical definitions of the terms, 
the most familiar example of a helix is a screw thread; of a plain 
spiral, a clock spring; of a conical spiral, a conical bed spring. 
By common acceptance, the word spiral, when applied to milling 
operations, gear teeth and cutters, means helical. 

This dividing head is an attachment so designed that, while 
holding the work, it will rotate it through any desired angle or 
fraction of a revolution. An example will be found in the rota- 
tion of a gear blank through an angle corresponding to the pitch; 
thus is the blank moved forward so that the cutter may form a 
new tooth. When cutting spirals suitable gears, mounted on a 
segment plate, are attached from the lead screw to the dividing 
head for rotating the dividing head spindle. Two tongues in the 
base of the head housing fit in the ''T'' slot of the table to which 
it is bolted. That the spindle may be inclined at any desired 
angle, it is carried on a swiveling block fitted in the housing. 
The same arbor and chuck which fit the main spindle will fit 
the head spindle, which is likewise hollow. The head spindle can 
be firmly locked during the cutting operations, thus relieving the 
worm, worm wheel and index pointer of all strain. Formed on 
this head spindle is a worm gear having 40 teeth, which arrange- 
ment necessitates, for one revolution of the spindle, 40 complete 
revolutions of the index pointer shaft, which is used in connection 
with an index plate, a sector and a pointer, for dividing the 
work. Thus one turn of the crank on the index pointer shaft 
gives :^X5 of a revolution of the spindle; two turns, ^q; four turns, 
iV, etc. For other divisions, the index plate, over which the 



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MILLING 307 

pointer crank turns, is used. This index plate is a circular disc 
on which a number of circles are arranged, each circle being divided 
by means of small, accurately sjiaced holes, into a different num- 
ber of equal parts. If the pointer on the crank be so adjusted 
that the pointer comes in line with the holes of any one circle, 
we may divide each revolution of the spindle into as many equal 
parts as 40 times that number of holes in the circle; or indeed 
any factor of that number of parts. 

The following is the method of procedure for obtaining any 
number of divisions (faces or teeth) of the circumference of the 
work. Consulting the table furnished with the machine, we find 
in the column headed "No. of Teeth or Divisions," the number 
we desire. On the same line in the next column headed ''Circle" 
is given the number of holes in the circle to which the index pointer 
must be set. In the third column headed "Turns" is given the 
number of complete revolutions of the pointer crank; and in the 
fourth column headed "Holes" is given the number of holes in 
that circle, to be added for each new setting. The function of the 
sector is to obviate the necessity of recounting each time this 
number of holes. In setting for a given number of holes, 12 for 
instance, a mistake is liable to be made in setting the sector, by 
including between its beveled edges but 12 holes; this is incorrect, 
for the hole in which the index pointer is inserted should never be 
counted when adjusting the sector. After the sector is set and 
tightened by the screw, no further counting of holes is necessary, 
because the sector, as set, is moved against the index pointer 
for each new division. 

When no table is available the setting may be easily calcu- 
lated as follows: write the fraction whose numerator is 40 and 
whose denominator is the number of teeth or divisions. This 
fraction represents the ratio that exists between the number of 
holes and the circle on which these holes are to be counted. 
Example: Required the setting for 180 divisions or teeth: ^Va = 
^\ = TMT = iJ» which means that if we select the circle marked 
18, we must use 4 holes; if 36 be selected, 8 holes, and if 54 be 
selected, 12 holes. Again, suppose that it is desired to obtain 
17 divisions: t? = SJ = W» which means that if we select the 
circle marked 17 we must use 40 holes on it; i.e., 2 turns plus 6 
holes; if 34 be the circle chosen, we must use 80 holes, which is 
two turns plus 12 holes. 



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308 ENGINEERING AND SHOP PRACTICE 

1324. Index Drum. In many machines, to facilitate the 
dividing of the work into parts less than 40, and to admit of 
starting the divisions at any desired point after the work has 
been set, an index drum, adjustable on and bolted to the spindle, 
is often used. 

1325. Tail-stock. The tail-stock furnished with the machine 
may be briefly described as follows: It is fastened to the table in 
the same manner as is the dividing head and carries two centers 
which are adjustable vertically and longitudinally by special 
adjusting knobs. Clamping bolts are provided for holding the 
centers firmly in position after they have been set. One center 
has the top milled off to allow small work, such as taps and 
reamers, to be milled; the other end is left as full as possible for 
heavy work. The change from one center to the other is easily 
effected. 

1326. Raising Block, For special work, generally chucked 
on the head, it is sometimes required that the axis of the head 
spindle be at an angle, in a horizontal plane, to the line of motion 
of the table. For such cases a raising block, a plate having two 
*'T" slots at right angles to each other, is used. This block is 
bolted to the table so that one of its ''T" slots forms the desired 
angle, and in this slot the head is bolted. 

1327. Swivel Vise. For holding a certain class of small work, 
a swivel or milling machine vise is used. This vise is so arranged 
that it can be rotated and clamped in any desired position on 
the table. 

1328. Steady Rest and Other Attachments. To prevent 
springing and chattering in such thin and slender work as is 
held between the centers, a steady or center rest is provided. 

The oil tank and drip cup should always be properly adjusted 
and used for all milling operations in wrought iron and steel. 

The other milling attachments, not furnished with the ma- 
chine, but which may be purchased, are the circular or rotary 
attachment, the vertical milling attachment, the profiling or cam- 
cutting attachment, the rack-cutting attachment, the high-speed 
attachment and the slotting attachment. 

1329. Characteristic Operations. It is important to under- 
stand the following operations and adjustments of the milling 
machine before starting to work: 

1. How to adjust the work in its relation to the cutter so 



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MILLING 309 

that, when possible, all the milling operations may be performed 
upon it without disturbing this adjustment, whether it be placed 
between centers, on the table, in the vise or in the chuck. 

2. How to select and assemble the proper cutters and arbors. 
The care and thought expended here is sure to be fruitful. 

3. The calculation and adjustments of the belts and gears 
to secure the proper cutting speeds and feeds. 

4. The means by which the various motions of the table are 
effected. 

5. The method of raising and lowering the saddle and the 
means of controlling the movement of the table. 

6. How to reverse the direction of the feed and the method 
of instantly stopping it. 

7. The method of determining, by means of the various dials, 
just that relation of the work to the cutter that will insure its 
operating where desired. 

8. A fundamental knowledge of the principle involved in the 
method of dividing with the dividing head, using either the dial 
or index drum. 

9. How to make the necessary gear calculations and adjust- 
ments for the various kinds of helical or spiral milling. 

10. The use of the raising block, swivel vise and steady rest. 

Milling 

133 1. Preparation of the Work. As was the case in the other 
machining operations before placing milling work in the machine 
in its proper relation to the cutter, it should be laid out to the 
drawing in accordance with the instructions given in Sees. 711 
and 712, Chapter VIL Of the varied stock which comes to be 
operated upon in the milling machine, unannealed tool steel is 
likely to give the most trouble on account of its liability of being 
either hard in spots or all over. Forgings, too, often offend in 
this manner, the hardness in any case resulting in a rapid dull- 
ing of the cutter. Both iron and steel castings usually possess 
a thin skin or scale which, because of its hardness and imbedded 
particles of sand, must be removed before a mill can operate 
successfully upon it. The accepted method of removing hard 
spots from tool steels is by annealing. Scale may be removed 
tolerably well by tumbling the smaller castings in a foundry rat- 
tler. A better method, and one adapted to larger castings and 



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310 ENGINEERING AND SHOP PRACTICE 

scaly forgings as well, is to pickle the castings, the process of 
pickling being as follows: the pieces so treated are washed with, 
or immersed in, a solution of 1 part of commercial sulphuric 
acid to from 4 to 10 parts of water. After the acid has had 
time to act — ten to fifteen minutes — the pieces are thoroughly 
washed in clean boiling water to remove all traces of the acid, 
which would otherwise cause them to rust rapidly. The crum- 
bling scale will now be found to be easily removed by means of 
wire brushes and old files. If, after pickling, the pieces are still 
too hard, they should be heated to a dull red heat and allowed 
to cool slowly, this annealing process tending, in addition to 
softening the piece, to release any shrinking and working strains 
that are inherent in it. 

1332. Nomenclature. — Terms and Operations Defined. When 
metal is removed by means of a cutting tool rotating about its 
axis and having one or more cutting edges, the operation is 
termed milling and the cutting tool is called a mill or cutter. 
Ordinary milling operations admit of the following classification: 
Face milling — machining a plane surface parallel to the axis of 
rotation of the cutter; side milling — machining a plane surface 
perpendicular to the axis of rotation of the cutter; ang^/ar mill- 
ing — the machining of a plane surface at an angle to the axis 
of rotation of the cutter; form milling — the machining of irregu- 
lar or curved surfaces having a profile similar to that of a cross- 
section of the cutter; grooving — the making of straight, **T/' 
irregular or helical slots or grooves; profiling — referring to such 
milling operations as require the use of a templet for guiding the 
work in any desired direction; routing — referring to such mill- 
ing operations as require that the work or the tool be fed by 
hand. 

1333. Influence of Cutter Diameters. The diameter of the 
milling cutter should be as small as the strength and convenience 
will permit. If it be desired to remove the amount of stock, 
1, 2, 3, 4, by one of the two cutters shown in Fig. 1333, it is 
obvious that the large cutter LC must travel the distance X 
during the operation, while the small cutter SC travels through 
the distance Y in performing the same operation; the small 
cutter thus efTecting a saving in time equivalent to the ratio 
which Z bears to X. If the length of the cut be short, the distance 
Z, the percentage saved, forms no inconsiderable portion of X, 



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MILLING 



311 



the total time. Again, small cutters cost less and require less 
power to drive them than large cutters. 




Fig. 1333. — Influence of Cutter Diameters. 



1334. Assembling Cutters, Collets^ CoilarSy etc. As has been 
stated before, in assembling the cutters, collets, collars and arbors 
they should be clean and carefully wiped dry to insure a true 
running cutter. A small piece of grit between the faces of the 
cutter and collar would cause the arbor to spring and the cutter 
to run out of true. 

1335. Feeding and Speeds. When it is desired to mill the 
end of a piece of work, the work should be so placed as to feed 
up and against the cutter as is the case in horizontal milling. 
This brings the pressure of the cut down upon the top of the 
table, with a tendency to close all the joints between the table, 
saddle and knee, insuring a smooth, steady cut. 

The following are the signs of excessive feed and speed: too 
high a cutting speed is attended by a rapid dulling of the cutter 
and subsequently a squeaking sound; slippage in the driving or 
feed belts may cause them to squeak or run off and is indicative 
of excessive feed. 

For knowledge relative to milling speeds and feeds the work- 
man is referred to Sees. 424 and 429 of Chapter IV. 

1336. End Milling Slots. When milling a slot with an end 
mill that necessitates the use of both sides of the cutter at the 
same time, the direction of the feed is determined from a consid- 
eration of the amount of stock to be removed from the sides; 
that surface from which the greatest amount of stock is to be 
removed should be fed against the cutter. The deeper cut against 



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312 ENGINEERING AND SHOP PRACTICE 

the cutter, with its tendency to retard the feed, reduces to a 
minimum the danger resulting from the drawing action of the 
lighter cut with the cutter. 

1337. Cutting Action of Face, Side and End Mills. Contrast- 
ing the action of face, side and end mills, we find that the ten- 
dency to spring and distort the work is greater with the face 
cutter, though the pressure is largely down or at right angles to 
the cut, while with the side and end mills the greatest pressure is 
in the direction of the feed. Face mills produce smoother sur- 
faces and require less care and grinding to keep them in good 
condition. 

1338. Swivel Vise Adjustments. When no zero mark is 
placed on the base of the vise, it may be adjusted to zero by 
placing between the centers a true, cylindrical piece of work and 
adjusting the vise so that the entire length of the jaw rests against 
the work. By the use of the try square, with the beam against 
the work and the blade agairist the inside of the jaw, a right 
angle to the first setting is obtained. Caution. For these opera- 
tions care should be taken to see that the table is set at the zero 
mark on the swivel carriage. 

1339. Order of Operations. Observe the following order of 
procedure when operating the milling machine for plain milling 
operations: 

1. Adjust the work. Adjust the work between the centers, on 
the table, in the vise, or in the chuck, using that form of device 
for holding it which seems, after due consideration, to be the best. 
Make sure that the work is immovable and securely fastened, 
and if between centers, that the tail of the dog is clamped with 
the set screw, and also that the tail center clamping bolts are 
tightened. If the work be held in the chuck, allow that portion 
to be milled to project away from the jaws. 

2. Select cutter. Select that milling cutter best adapted, as 
to kind and diameter, for the work in hand. Place it on the arbor 
as close to the spindle as possible and so that, when running 
normally J the teeth cut down. Before assembling, the arbor, collet 
or socket, cutters, bushings and bearings should be wiped dry with 
clean waste. Insert the arbor in the spindle, oil the outer end 
and adjust it in the overhanging arm, clamping the arm when in 
position. 

3. Adjust table and carriage. In order to bring the work into 



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MILLING 313 

its proper relation with the cutter, adjust the table and the 
carriage so that the work feeds against the cutter, i.e., the work 
to the right of the cutter when the latter is rotating to the left 
(Fig. 1339). To avoid accident or irregularity with the cut, take 
up all back-lash of the lead and cross-feed screws. As all the 
adjustments are given on the dials in thousandths of an inch, we 
may use them, in some instances at least, for determining ap- 




FiQ. 1339. 

proximate dimensions and cut depths. In working from the cen- 
ter, the table is adjusted until the cutter, or the side of the 
cutter, is central; in this position the pointer is set to the zero on 
the dial, when the screw is turned a distance equal to half the 
width of the piece. As this method of setting is somewhat inac- 
curate, it is better to err on the safe side and to check all meas- 
urements with the scale. 

4. Determine speed and feed. After having selected the proper 
speed and feed by calculation or from the tables in Sees. 424, 
428 and 429, Chapter IV, which deal with milling speeds and feeds, 
adjust both the driving and feeding belts or feed box. 

5. Adjust the stop. Adjust the trip dog or stop so as to dis- 
engage the automatic feed before the cutter meets any obstruction, 
i.e. J at the end of the cut. 

6. Ascertain correctness of adjustments. If necessary, lower 
the knee and run the work past the cutter, both to determine the 
correctness of the adjustments and to see whether any obstruction 
to the cut will be met with during the operation. If this be 
done the work must be brought back to its original position, the 
knee raised and all backlash taken up. 

7. PvU over by hand. With all adjustments made, pull over 
by hand to ascertain their correctness and to avoid breakage. 



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314 



ENGINEERING AND SHOP PRACTICE 



8. Determine cut dejyth. Determine the depth of the trial cut 
by measurement. 

9. Adjust drip pan and oil tank. For wrought iron or steel 
adjust the oil tube over the cutting sido-of the mill and place the 
drip pan where it will catch the waste oil and chips; lard oil 
should be used. Open the oil valve to about thirty drops per 
minute. Flooding is generally beneficial. 

10. Start the machine. Do not feed by hand, as any careless- 
ness may result in pushing the work in deeply between two 
adjacent cutter teeth with the result that the work will be spoiled, 
the cutter broken, or both. 

11. Throw in the feed. Throw in the automatic feed and allow 
the work to feed up to the cutter; watch the work carefully to 
detect any irregularity in the working of the machine. Be ready 
to take advantage of every opportunity to save time. 

Examples of Milling 

1341. Face Milling. Figs. 1341a and b illustrate the ordinary 
methods of milling hexagon nuts or bolt heads. In the first 





FIG. 1341a FIG. 1341b 

Figs. 1341a, b. — Face Milling Nut and Bolt Heads. 

illustration a face mill is used, and one surface is finished at a 
time. The straddle mills or cutters in the other example are 
side mills arranged for finishing two sides at one operation. In 
either case a number of nuts may be strung on an arbor or man- 
drel and all finished at one time. 

Fig. 1341c illustrates the method of milling a number of 
small pieces and accurately finishing the sides and bottom at 
one operation. 

1342. Slot Milling. Fig. 1342a illustrates the final operation 
in the milling of a *'T" slot, the preliminary operation consisting 
in the removal of all metal possible by means of a face cutter, 
If a face cutter cannot be used to advantage, the stock may be 



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MILLING 315 



Fig. 1341c. — Face Milling Several Pieces. 



Fig. 1342a. — T-slot Milling, Final Operation. 



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316 ENGINEERING AND SHOP PRACTICE 



Fig. 13426. — MUling Dovetail Slots. 



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MILLING 317 

removed with an end mill, whose diameter is somewhat smaller 
than the width of the slot. 

Fig. 13426 illustrates the final operation in the milHng of a 
dovetail slot, the preliminary operation being the same as that 
for milling the "T" slot. 

1343. Boring and Facing. Fig. 1343a illustrates the method 
of milling the bearing of an engine, finishing both the sides and 
the bottom at one operation. The figure is suggestive of the 
variety of work that may be performed on a milling machine with 
one chucking and cut. 

Fig. 13436 is suggestive of the various boring, facing and 
milling operations which may be performed to advantage by 
either bolting the work to the table, holding it in the vise or 
between the centers. For long holes it is well to support the 
outer end of the boring bar arbor in the overhanging arm. It 
may be noted from this suggestion that by using the vertical and 
lateral adjustments, work may be readily and speedily set in 
any desired position for boring parallel holes. In all settings of 
the table, care should be taken to eliminate all errors that might 
be due to backlash in the various adjusting screws. In this 
operation a twist drill or reamer may advantageously take the 
place of a cutter or boring bar. 

1344. Key- seating and Fluting. Fig. 1344a illustrates the 
method of milling several key-seats; with a single piece this may 
be done by holding the shaft in a vise or between the centers. 

Fig. 13446 illustrates the method of fluting cutters, taps and 
reamers. In the case of tapered work the tail center is raised 
enough to give the proper depth of cut at each end of the flutes. 

1345* Cjear Cutting, Segment and Spot Finishing. Fig. 
13446 is also illustrative of the method of cutting a gear or number 
of gears; when two or more gears are to be cut they are strung 
on an arbor or mandrel and placed between the centers, the 
table having previously been adjusted so that the center line of 
the gear blanks is directly underneath the center line of the 
cutter. The dividing head is then adjusted to give the correct 
number of divisions and the table raised until the cutter just 
touches the rim of the gear blank. Set the graduated dial on 
the elevating screw to zero, run the blanks out from under the 
cutter to the proper side and raise the table an amount equal to 
the required depth of tooth (this latter is generally marked on 



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318 ENGINEERING AND SHOP PRACTICE 



Fig. 1343a. — Face and Side Milling Engine Bearings. 



Fig. 13436. — Boring and Facing Operations. 



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MILLING 319 



Fig. 1344a. — Key-seating Several Shafts at once. 



Fig. 13446. — Fluting a Milling Cutter. 



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320 ENGINEERING AND SHOP PRACTICE 



Fig. 1345a. — Milling Clutch Teeth. 

the cutter). By bringing the index or dividing head spindle 
into a vertical position, we have a means whereby spur gears, 
and work too large to bs swung between the centers, may be 
operated upon. The blanks are carried on a vertical arbor in- 
serted in the spindle; this placing of the blanks in a horizontal 
position necessitates the determination of the tooth depth by 
means of the lead screw, and of the work being fed by the vertical 
feed or elevating screw. Fig. 1345a illustrates the method of 
milling clutch teeth. 

Fig. 13456 illustrates the method — with a vertical milling 
machine — of end- and side-mill finishing a horizontal plane 
surface and a vertical segment at one operation. 

Fig. 1345c illustrates the method — with a vertical milling 
machine — of finishing spots on the inside surface of a feed- 
bracket casting with an end mill. The same cutter also finishes 
the upper edge of the casting. This gives an economy over 
counterboring of ten to one. 



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MILLING 321 



Fio. 13456. — Segment Milling. 



Fig. 1345c. — Spot Facing. 



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322 



ENGINEERING AND SHOP PRACTICE 



1346. Mobbing a Worm Wheel. Fig. 1346 illustrates the 
method of hobbing a worm wheel after the teeth have been 
gashed. The gashing of the worm blank is accomplished by 
placing it on an arbor between the centers and treating it as if 
it was an ordinary gear, with the exceptions that such a gear 
cutter be selected as to leave just enough stock for the finishing 
cut with the hob; and it is necessary to swivel the table through 



Fig. 1346a. — Hobbing a Worm Wheel. 

an angle whose magnitude depends upon the pitch and diameter 
of the worm. Owing to the shape of the face of the worm gear 
it cannot be fed to the cutter in a manner similar to that used 
for spur-gear operations, but must be fed to the cutter to the 
desired depth, and then dropped and indexed for each succeeding 
cut. Swivel the table to the right for a right-handed worm 




Fig. 134G/>. 

thread and to the left for the left-handed thread. For the final 
operation of hobbing, the carriage and table are brought back to 
zero. The determination of the angle through which the table is 
swiveled is as follows: Lay off the distance A B equal to the pitch 
and the distance AC at right angles to AB (Fig. 13466). AC '\8 
the result obtained by multiplying the pitch diameter of the worm 
by 3.1416. Connect the points C and B with a straight line; then 
the angle ACB gives the number of degrees through which the 
table must be swiveled. 



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MILLING 



323 



1347. Cutting Bevel and Miter Gears. Fig. 1347a illustrates 
the method of setting for cutting bevel and miter gears. The 
blank is mounted on a suitable arbor held in the chuck or spindle; 
the spindle is then swung around in the head until the root line 
of the tooth is parallel with the table top. The proper cutter 
should now be selected, placed on the cutter arbor and brought 
central with the work. The following is a rule for determining 
the selection of a cutter for bevel gears. Divide the number of 




Fig. 1347a. — Cutting Bevel and Miter Gears. 

teeth of the bevel gear by the natural cosine of the center angle 
(y 2 in Fig. 13476), this gives the number of teeth in the fictitious 
gear for which a standard cutter for this number of teeth is 
selected. When working from a drawing, twice the slant height 
of the back cone yz multiplied by the diametral pitch gives the 
number of teeth in the fictitious gear for which the cutter is to 
be selected. Below is outlined the ordinary method of .procedure 

— using the above-mentioned rule for the ^selection of the cutter 

— when cutting bevel and miter gears with a single cutter; the 



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324 ENGINEERING AND SHOP PRACTICE 

teeth so cut are sufficiently exact for ordinary purposes, though 
being of but approximately correct outline. For a given pitch, 
in bevel and miter gears, the depth and width at the outer end 
of the tooth is the same as for spur gears. As the convergenre of 
the teeth renders the inner end of the tooth portion narrower, the 
cutters for bevel gears must be thinner than for spur gears; hence 
the foregoing rule for selecting cutters of correct thickness. 



Fig. 13476. 

With the index pointer set for the proper number of teeth, 
two center cuts are taken; the blank is then moved off center a 
few thousandths of an inch (say ^ the tooth thickness) and the 
index pointer advanced until the cutter will enter the small end 
of one of the central cuts. The object of this latter setting is to 
remove stock from the side of the tooth, taking more at the outer 
end than at the inner. To take the cut on the opposite side of 
the tooth, the blank is moved back double the amount it had 



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MILLING 325 

been moved out and the pointer set back twice the number of 
holes it had been advanced. If, upon measuring the thickness 
of the tooth at the outside, it is found to be more than the quo- 
tient obtained by dividing the circumference of the pitch circle 
by twice the number of teeth, the blank must be set farther off 
center. It may be well to state that no empirical rule exists for 
these settings, and that the tooth must be measured after each 
trial setting is taken. Attention is called to an A. S. M. E. paper, 
December, 1896, in which Forrest R. Jones and Arthur L. Goddard 
relate some experimental investigations to find a graphical method 
of determining these operations. This paper was published in 
the American Machinist of January 21, 1897. However, after the 
proper setting for any particular gear is had, the center cut is 
unnecessary, as the tooth may be finished by the two side cuts. 
A record of the successful setting should always be kept for 
future reference. For a more complete description of the pro- 
cesses of cutting bevel gears the student is referred to the Brown 
& Sharpe Treatises on Gearing. 

1348. Helical Grooving. Fig. 1348a and 13486 illustrate the 
method of cutting helical grooves such as those of twist drills or 
spiral milling cutters. In this operation it is necessary to impart 
to the work rotary motion as well as longitudinal; this is accom- 
plished by connecting the lead screw with the dividing head 
spindle by means of change gears. A table of change gears for 
spiral milling is always furnished with the machine. The dis- 
tance the helix (spiral) advances in one revolution is called the 
lead (pitch). The following data are requisite before work of 
this character may be undertaken: the lead or pitch of the spiral, 
the spiral angle, and the number of teeth or grooves to be cut. 
After the work is placed between the centers, the change-gear 
table is consulted and the change gears adjusted; the table is 
then swung through an angle equal to that of the spiral angle. 
Right-handed spirals require that the rotation of the dividing 
head spindle be right-handed and nice versa; a change in the 
direction of rotation being effected by inserting or omitting an 
idler-gear in the change-gear mechanism. In fluting twist drills 
it is necessary to elevate the point in order that the web between 
the flutes may be thicker toward the shank, as is the case in ordi- 
nary practice. 



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326 ENGINEERING AND SHOP PRACTICE 



Fig. 1348a. — Milling a Spiral Cutter. 



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MILLING 



327 




Fia. 13486. — Milling a Twist Drill. 



1349. Backing Off Drill Lands. Relieving the drill, i.e., 
backing off the lands, is a distinctive and somewhat difficult 
operation; the method is illustrated in Fig. 1349. The table is 
swung through a small angle indicated by the line BA; this 
causes the end mill, the cutter used for this operation, to cut 
deeper at C than at D, thus producing the desired relief or clear- 
ance. 



Fig. 1349. — Backing off Drill Lands. 
GlOAKING 

1351. The Sizing and Cutting of Gear Wheels. (From 
Brown & Sharpens Catalogue.) The word '* diameter '' when applied 
to gears is always understood to mean the pitch diameter. 



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328 ENGINEERING AND SHOP PRACTICE 

Diametral pitch of the gear is the number of teeth to each 
inch of its pitch diameter. If a gear has 40 teeth and the pitch 
diameter is 4^^, there are 10 teeth to each inch of the pitch diameter, 
and the diametral pitch is 10, or in other words the gear is 10 
diametral pitch. 

Circular pitch is the distance from thie center of one tooth to 
the center of the next tooth, measured along the pitch circle. If 
the distance from the center of one tooth to the center of the 
next tooth, measured along the pitch circle, is J'^, the gear is 
i" circular pitch. 

The diametral pitch given, to obtain the circular pitch, divide 
3.1416 by the diametral pitch. If the diametral pitch is 4, 
divide 3.1416 by 4, and the quotient, .7854*, is the circular pitch. 

The circular pitch given, to obtain the diametral pitch, divide 
3.1416 by the circular pitch. If the circular pitch is 2", divide 
3.1416 by 2 and the quotient, 1.5708, is the diametral pitch. 

The number of teeth and the diametral pitch given, to obtain 
the pitch diameter, divide the number of teeth by the diametral 
pitch. If the number of teeth is 40 and the diametral pitch 4, 
divide 40 by 4 and the quotient 10 is the pitch diameter. 

The number of teeth and the diametral pitch given, to obtain 
the whole diameter or size of blank or gear, add 2 to the number 
of teeth and divide by the diametral pitch. If the number of 
teeth is 40 and the diametral pitch is 4, add 2 to the 40, making 
42, and divide by 4; the quotient, lOi, la the whole diameter of 
the gear or blank. 

The number of teeth and the diameter of the blank given, to 
obtain the diametral pitch, add 2 to the number of teeth, and 
divide by the diameter of the blank. If the number of teeth is 
40, and the diameter of the blank is lOJ'', add 2 to the number 
of teeth, making 42, and divide by lOJ; the quotient, 4, is the 
diametral pitch. 

The pitch diameter and the diametral pitch given, to obtain 
the number of teeth, multiply the pitch diameter by the diametral 
pitch. If the diameter of the pitch circle is lO'', and the diametral 
pitch is 4, multiply 10 by 4, and the product, 40, will be the 
number of teeth in the gear. 

The whole diameter of the blank and diametral pitch given, 
to obtain the number of teeth in the gear, multiply the diameter 
by the diametral pitch and subtract 2. If the whole diameter 



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MILLING 329 

is lOJ'' and the diametral pitch is 4, multiply lOJ by 4, and the 
product 42, less 2, or 40, is the number of teeth. 

The thickness of a tooth at the pitch line is found by dividing 
the circular pitch by 2, or by dividing 1.57 by the diametral 
pitch. If the circular pitch is 1.047'^, or the diametral pitch is 3, 
divide 1.047 by 2, or 1.57 by 3, and the quotient, .523^ is the 
thickness of tooth. 

The whole depth of a tooth is found by dividing 2.157 by the 
diametral pitch. If the diametral pitch of a gear is 6, the whole 
depth is 2.157 divided by 6, or .3595. The whole depth of a tooth 
is about \i or exactly .6866 of the circular pitch. If the circular 
pitch is 2, the whole depth of tooth is about |i of 2 inches or 
nearly If''. 

The distance between the centers of two gears is found by 
adding the number of teeth together, and dividing half the sum 
by the diametral pitch. If two gears have 50 and 30 teeth 
respectively, and are 5 pitch, add 50 and 30, making 80; divide 
by 2, and then divide the quotient, 40, by the diametral pitch, 5, 
and the result, 8^^, is the center distance. 



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330 



ENGINEERING AND SHOP PRACTICE 



1352. Table of Gear Tooth Parts. 















Addendum 




Threads 
or Teeth 

per Ib. 

linear 


Qrcular 

Pitch 

in 

Decimals 


Circular 

Fitch in 

Inches and 

Fractions 


Diametral 
Pitch 


Thickness 

of Tooth 

on Pitch 

Line 


Whole 

Depth of 

Tooth 


Height 
above the 
Pitch Line 


Depth of 
Space Be- 
low Pitch 
Line 


i 


2.000 


2 


1.571 


1.000 


1.3732 


.6366 


.7366 


■h 


1.875 


li 


1.675 


.9375 


1.2874 


.5968 


.6906 


i 


1.750 


u 


1.795 


.8750 


1.2016 


.5570 


.6445 


tV 


1.625 


ll 


1.933 


.8125 


1.1158 


.5173 


.5986 


1 


1.500 


u 


2.094 


.7500 


1.0299 


.4775 


.5525 


II 


1.437 


lA 


2.185 


.7187 


.9870 


.4576 


.5294 


A 


1.375 


i| 


2.285 


.6875 


.9441 


.4377 


.5964 


M 


1.312 


lA 


2.393 


.6562 


.9312 


.4178 


.4834 


* 


1.250 


li 


2.513 


.6250 


.8583 


.3979 


.4604 


iJ 


1.187 


lA 


2.646 


.5937 


.8156 


.3780 


.4374 


} 


1.125 


U 


2.792 


.5625 


.7724 


.3581 


.4143 


i? 


1.063 


lA 


2.957 


.5312 


.7295 


.3382 


.3913 


1 


1.000 


1 


3.142 


.5000 


.oyoo 


.3183 


.3683 


lA 


.937 


H 


3.351 


.4687 


.6437 


.2984 


.3453 


U 


.875 


i 


3.590 


.4375 


.6007 


.2785 


.3223 


lA 


.812 


il 


3.836 


.4062 


.5579 


.2588 


.2993 


U 


.750 


} 


4.189 


.3750 


.5150 


.2387 


.2762 


lA 


.687 


H 


4.569 


.3437 


.4720 


.2189 


.2532 


IJ 


.666 


i 


4.712 


.3333 


.4577 


.2122 


.2455 


If 


.625 


i 


5.026 


.3125 


.4291 


.1989 


.2301 


li 


.562 


A 


5.585 


.2812 


.3862 


.1790 


.2071 


2 


.500 


1 


6.283 


.2500 


.3433 


.1592 


.1842 


2J 


.437 


A 


7.181 


.2187 


.3003 


.1393 


.1611 


2i 


.400 


! 


7.854 


.2000 


.2746 


.1273 


.1473 


2* 


.375 


i 


8.377 


.1875 


.2575 


.1194 


.1381 


3 


.333 


i 


9.425 


.1666 


.2289 


.1061 


.1228 


3i 


.312 


A 


10.053 


.1.562 


.2146 


.0995 


.1151 


31 


.285 


* 


10.995 


.1429 


.1962 


.0910 


.1052 


4 


.250 


i 


12.566 


.1250 


.1716 


.0796 


.0921 


4i 


.222 


J 


14.137 


.1111 


.1526 


.0707 


.0818 


5 


.200 


i 


15.708 


.1000 


.1373 


.0637 


.0737 


5J 


.187 


A 


16.755 


.0937 


.1287 


.0597 


.0690 


6 


.166 


i 


18.8.50 


.0833 


.1144 


.0531 


.0614 


7 


.142 


i 


21.991 


.0714 


.0981 


.0455 


.0526 


8 


.125 


I 


25.133 


.0625 


.0858 


.0398 


.0460 


9 


.111 


i 


28.274 


.0555 


.0763 


.0354 


.0409 


10 


.100 


A 


31.416 


.0500 


.0687 


.0318 


.0368 


16 


.062 


A 


50.265 


.0312 


.0429 


.0199 


.0230 

















_ 






Fig. 1352. 



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BULLING 



331 



1353. Odontographies (Laying out gear teeth). — Grant's 
Cycloidal System. Taken from Machinery Data Sheets. The 
three-point odontograph, devised and calculated by Geo. B. 
Grant, is one of the best methods for laying out accurate gear 
teeth or the templates for gear teeth. The odontograph gives 
the centers and radii for drawing circular arcs which approximate 
the actual tooth curves. 

To apply the odontograph to any particular case of cycloidal 
teeth, first draw the pitch, addendum (height above pitch line), 
root and clearance circles or lines, and space the pitch lines for 
the teeth in the usual way; then draw the line of flank centers at 
the tabular distance, outside of the pitch line, and the line of 
face centers inside of it. Take the face radius on the dividers 
and draw in all the face curves from centers on the line of face 
centers; then take the flank radius and draw all the flank curves 
from centers on the line of flank centers. 

The table (Fig. 1354) gives the distances and radii if the pitch 
is either exactly one diametral or one inch circular, and for any 
other pitch multiply or divide as directed in the table. 



fjn eoty^*"^ Centera 




Fig. 1353. — Grant's Cycloidal Layout. 



The odontograph may also be applied to laying out teeth for 
internal gears. 



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332 ENGINEERING AND SHOP PRACTICE 

1354. Table for Cycloidal Teeth. 



Number 

THE 


F Teeth nt 
Geak 


For One Diametral Pitch. 

For any other Pitch Divide by 

THAT Pitch 


For One Inch Circular Pitch. 

For any other Pitch Multiply 

BY THAT Pitch 




Faces 


Flanks 


Faces 


Fbnks 


Exact 


Intervals 


Rad. 


Dis. 


Rad. 


Dis. 


Rad. 
.62 


Dis. 
.01 


Rad. 
-2.55 


Dis. 


10 


10 


1.99 


.02 


- 8.00 


4.00 


1.27 


11 


11 


2.00 


.04 


-11.05 


6.50 


.63 


.01 


-3.34 


2.07 


12 


12 


2.01 


.06 






.64 


.02 






13i 


13— 14 


2.04 


.07 


15.10 


9.43 


.65 


.02 


4.80 


3.00 


15i 


15— 16 


2.10 


.09 


7.86 


3.46 


.67 


.03 


2.50 


1.10 


17i 


17— 18 


2.14 


.11 


6.13 


2.20 


.68 


.04 


1.95 


.70 


20 


19— 21 


2.20 


.13 


5.12 


1.57 


.70 


.04 


1.63 


.50 


23 


22— 24 


2.26 


.15 


4.50 


1.13 


.72 


.05 


1.43 


.36 


27 


25— 29 


2.33 


.16 


4.10 


.96 


.74 


.05 


1.30 


.29 


33 


30— 36 


2.40 


.19 


3.80 


.72 


.76 


.06 


1.20 


.23 


42 


37— 48 


2.48 


.22 


3.52 


.63 


.79 


.07 


1.12 


.20 


58 


49- 72 


2.60 


.25 


3.33 


.54 


.83 


.08 


1.06 


.17 


97 


73—144 


2.83 


.28 


3.14 


.44 


.90 


.09 


1.00 


.14 


290 


145—300 


2.92 


.31 


3.00 


.38 


.93 


.10 


.95 


.13 




Rack 


2.96 


.34 


2.96 


.34 


.94 


.11 


.94 


.11 



Fio. 1354. 

1355. Grant's Involute System. To draft the tooth lay off 
the pitch, addendum, root and clearance lines, and space the 
pitch line for the teeth. 




FiQ. 1355. — Grant's Involute Layout. 



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MILLING 333 

Draw the base line one sixtieth of the pitch diameter inside 
the pitch line. 

Take the tabular face radius on the dividers, after multiplying 
or dividing it as required by the table (Fig. 1358), and draw in 
all the faces from the pitch line to the addendum line from centers 
on the base line. 

Set the dividers to the tabular flank radius, and draw in all 
the flanks from the pitch line to the base line. 

Draw straight radial flanks from the base line to the root line, 
and round into the clearance line. 

1356. Laying Out the Involute Rack. Draw the sides of the 
rack tooth as straight lines inclined to the lines of centers at an 
angle of fifteen degrees, which is best found by quartering the 
angle at sixty degrees. 

Draw* the outer half of the face, one quarter of the whole 
length of the tooth, from a center on the pitch line, with a radius 
of 

2.10 inches divided by the diametral pitch. 
.67 inches multiplied by the circular pitch. 

1357. Laying Out Internal Involute Gears. When the internal 
gear is to be drawn, the odontograph should be used as if the 
gear was an ordinary external gear; but care must be taken that 
the tooth of the gear is cut off to. avoid interference. The point 
of the tooth may be left off altogether or rounded over to get 
the appearance of a long tooth. ^The pinion tooth need not be 
carried in to the usual root line, but may just clear the truncated 
tooth of the gear. The curves of the internal tooth and of its 
pinion may best be drawn in by points, for the odontographic 
corrected tooth is not as well adapted to the place as the true 
tooth, and no correction for interference is needed on the points 
of the pinion teeth or on the flanks of those of the gear. 



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334 



ENGINEERING AND SHOP PRACTICE 



1358. Table for Involute Teeth. 





Divide by the Diametkal Pitch 


Multiply by the Cikcular Pitch 


Teeth 












Face Radius 
2.28 


Flank Radius 


Face Radius 


Flank Radius 


10 


.69 


.73 






.22 


11 


2.40 




.83 


.76 






.27 


12 


2.51 




.96 


.80 






.31 


13 


2.62 




1.09 


.83 






.34 


14 


2.72 




1.22 


.87 






.39 


15 


2.82 




1.34 


.90 






.43 


16 


2.92 




1.46 


.93 






.47 


17 


3.02 




1.58 


.96 






.50 


18 


3.12 




1.69 


.99 






.54 


19 


3.22 




1.79 


1.03 






.57 


20 


3.32 




1.89 


1.06 






.60 


21 


3.41 




1.98 


1.09 






.63 


22 


3.49 




2.06 


1.11 






.66 


23 


3.57 




2.15 


1.13 






.69 


24 


3.64 




2.24 


1.16 






.71 


25 


3.71 




2.33 


1.18 






.74 


26 


3.78 




2.42 


1.20 






.77 


27 


3.85 




2.50 


1.23 






.80 


28 


3.92 




2.59 


1.25 






.82 


29 


3.99 




2.67 


1.27 






.85 


30 


4.06 




2.76 


1.29 






.88 


31 


4.13 




2.85 


1.31 






.91 


32 


4.20 




2.93 


1.34 






.93 


33 


4.27 




3.01 


1.36 






.96 


34 


4. .33 




3.09 


1.38 






.99 


35 


4.39 




3.16 


1.39 






l.Ol 


36 


4.45 




3.23 


1.41 






1.03 


37— 40 




4.20 




1.34 




41— 45 




4.63 




1.48 




46— 51 




5.06 




1.61 




52 - 60 




5.74 




1.83 




61— 70 




6.52 




2.07 




71— 90 




7.72 




2.46 




91—120 




9.78 




3.11 




121—180 




13.38 




4.26 




181— 3(K) 




21.62 

Fig. 1358. 




6.88 

















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MILLING 



335 



1359. Gearing NoteSi Strength, Speed and Horse-power. In 

a paper before the Engineers' Club of Philadelphia, Wilfred 
Lewis develops the formula, W = «p/y, for strength of gear 
teeth, under the following assumptions: (1) that the load trans- 
mitted, TF, is well distributed across the tooth instead of at one 
comer; (2) that the whole load is taken by one tooth and that 
this tooth is considered as a beam loaded at one end. From a 
series of drawings of teeth of involute, cycloidal and radial flank 
systems, he determines the point of weakest cross-section of each 
and the ratio of the thickness at that section to the pitch. In 
the formula, W = «p/y, W = load transmitted in pounds; « is 
the safe working stress of the material and is taken from the 
table, Fig. 1359&, which has been arranged to conform to the 
curve on the chart. Fig. 1359a; p == circular pitch in inches; 
/ = face in inches; and t/ = a factor depending upon the form of 
the tooth and which may be calculated closely by the formulas, 

912 
For involute, 20° obliquity, y = .154 — - — 

684 
For involute, 15° and cycloidal, y = .124 — 



For radial flank. 



y = .075 - 



.276 



n being the number of teeth in the gear. 







Safe Working Stress, 


S for Different Speeds 




Speed ofTeethinFt. 
perMin.or leas. . . 


100 


200 


300 


600 


900 


1,200 


1,800 


2,400 


Cast Iron 


7,000 
17,500 


6,000 
15,000 


5,3r>0 
13,375 


4,000 
10,000 


3.250 

8,125 


2,700 
6,750 


2,000 
5,000 


1,650 


Steel 


4,125 







Fio. 13596. 



Having determined the strength of the gear, we easily develop 
the following formula for the horse-power transmitted: 



HP = 



Wv 



.W 



33,000 HP 



= sp/y, sp/t/t; = 33,000 HP 



33,000' V 

from which Mr. Lewis' general formula may take the form, 



HP 



00 rw^*" which V = the velocity in ft. per minute: since, 
00,000 



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336 ENGINEERING AND SHOP PRACTICE 



G 

Q 



b o 



<3 3 

1:2 



H 



■s 

o 

I 



o 



I 



u6ji > 

1B«D ui naji|6 | 



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MILLING 337 

TT dia. X rev. per min. ocic j v^ • j u 

V = j^"^- , V = .2616a X rev. rep mm. and we have, 

„p _ sj)fy X .2618 (f X rev, per min. _ spjy X d X r ev, per min. 

33;606 1267)50 

= .000,007,933 d spfy X rev. per min. 

Arbors and Milling Cutters in General 

1361. Arbors — Description and Use. The fimction of the 
milling machine arbor is to hold and rotate the milling cutter. 
The ordinary design has at one end a Brown & Sharpe taper 
similar in shape to a twist drill shank, and ground to fit a corre- 
sponding tapered hole in the spindle. That portion of the arbor 



^ 




B *n-^ V-D--N 




FiQ. 1361. — Milling Machine Arbor. 



projecting from the spindle and designed to carry the cutters is 
cylindrical, and carries a number of different width removable 
collars or washers, between which the cutter is clamped in any 
desired position. At either end of the straight portion, carrying 
the washers, is a threaded portion and nut; the nut nearest the 
tapered portion is used in removing the arbor from the spindle, 
the other nut for clamping the washers and cutter. Ordinarily 
the cutter is driven by the friction that exists between it and the 
washers, which is created by tightening the nut on the outer end 
of the arbor. A washer of ordinary writing paper, placed on 
either side of a cutter that persistently slips, will, in most cases, 
remedy this difficulty. For heavy work the cutter should be 
keyed to the arbor. If the thread on the outer end of the arbor 
be right-handed, a right-handed cutter should be used so that 
any tendency in the cutter to slip will tighten the nut. 

1362, Shell Mill and Screw Arbors. Shell mill and screw 
arbors are designed for holding shell end milling cutters. By 
their use a saving in the cost of cutters is effected, for only that 
portion of the cutter designed for cutting need be of fine tool 
steel. This class of arbors and all stem or shanked cutters must 
be securely seated in the taper in the spindle. 



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338 



ENGINEERING AND SHOP PRACTICE 



< 



CM 



Fig. 1362a. — Arbor for SheU End Mills. 



a 



□ 



FiQ. 13626. — Milling Machine Screw Arbor. 

1363. Collets. Collets, similar to drill collets, are used in the 
same manner and for the same purpose on milling machine arbors 
and stem or shanked cutters. Brown & Sharpe tapers d" per 
foot) are in general use for milling arbors and collets. 



C^ 




^I 



Fig. 1363. — CoUets. 



3 



1364. Classification and Design of Cutters and Mills. Cut- 
ters are generally classed, according to the milling operations 
which they perform, into face or axial, side or radial, angular, 
end and form milling cutters; and again according to their con- 
struction, into solid, inserted tooth, stem or shanked, and end or 
shell end cutters. Cutters are also said to be right- or left-handed 
in accordance with their direction of rotation when cutting. 
This latter classification has reference in general to shanked or 
stem cutters, the majority of arbor-driven cutters being rever- 
sible. With the operator in front of and facing the machine, 
and the cutter adjusted, if, in order to cut, it must rotate in the 
direction opposite to the hands of a clock, it is a right-handed 
cutter, and vice versa. 

The pitch of a cutter is the distance between two adjacent 
cutting edges. Ordinarily the front face of the milling cutter is 
cut radial; the top face is ground with from 3° to 5° clearance. 



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Fig. 1364. — A Page of Milling Cutters. 



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340 ENGINEERING AND SHOP PRACTICE 

or at an angle of 85° to 87° with the front face. The back face is 
usually cut at an angle of 52° with the front face. 

1365. Care of Cutters. There are two general conditions 
which govern the efficient operation of a milling cutter: (1) It is 
absolutely essential that it be kept sharp. (2) That its cutting 
edges are equidistant from the axis of rotation. Never run a 
cutter backward; an endeavor to do so generally results in broken 
teeth. The disadvantages of dulness may be summed up as 
follows: poor work, more power required, the additional loss of 
temper in the cutter and elsewhere, and a general dissatisfaction 
to all concerned. 

* Milling Cutters — Specific 

1371. Face Milling Cutters. Axial cutters that are intended 
for milling surfaces parallel to their axes of rotation are termed 
face-milling cutters. In general cutters of this class, under one 
inch in width, have straight cutting edges, i.e., parallel to the 
axis of rotation. Wider cutters usually have helical cutting 
edges whose action may be contrasted as follows with that of 
those having straight cutting edges. With the straight-edged 



Fig. 1371. — Face Milling Cutters. 

cutter each cutting eJg3 strikes a distinct blow over the entire 
width, while with the spiral tooth cutter the action, commencing 
at one corner and proceoding across the surface of the work, is 
more that of shaving than chipping. Wide cutters usually have 
nicked teeth (cutting edges) for breaking up the chip; for this 
reason a cutter with nicked teeth requires less power to drive it, 
and consequently, with a given amount of power, heavier cuts 
may be taken with a nicked cutter. 



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MILLING 341 

1372. Side Milling Cutters. Side or straddle milling cutters 
are designed for milling surfaces perpendicular to the axis of 
rotation of the cutter, and differ from the face mills in that they 



Fig. 1372. — Side or Straddle Milling Cutter. 

have cutting edges formed on their sides in addition to those on 
the periphery. With this class of cutter the work may be fed 
either against the face teeth or against the side teeth as desired. 
1373. Angular Milling Cutters. Angular milling cutters are 
divided into single and double angle cutters according as they 
possess one •or two cutting edges and are designed for milling 
surfaces at an angle to the axis of rotation of the cutter. If the 
angle included between the perpendicular to the axis of rotation 
and the inclined edge is a 45° or 60° angle, the cutter is designated 



Fig. 1373. — Angular Milling Cutter. No. 1 
Right, and No. 2, Left Hand. 

as a 45° or 60° cutter. If the angle on one side of the perpendicular 
of a double angle cutter be 12° and the angle on the other side 
be 40°, the cutter is designated as a 12°, 40° double-angle cutter; 
such a cutter is used for cutting the teeth grooves of a spiral 
(helical) cutter. 



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342 ENGINEERING AND SHOP PRACTICE 

1374. End Milling Cutters. The term end mill has reference 
in general to such stem or shanked cutters as are held directly in 
the spindle and used for end and slot milling. In construction 
they are a combination of the side and face milling cutters. The 
larger end mills are made hollow and are screwed or otherwise 
fastened to the taper shank; these are termed shell end mills. 




Fig. 1374. — Right-hand End Mill. 

"T" slot cutters, as their name indicates, are used for cutting 
*'T" slots and are shanked similar to end mills. 

1375. Form Milling Cutters and Formed Cutters. Form 
milling cutters are designed for milling irregular or curved sur- 
faces. The term form cxUter is usually applied to such cutters as 
have cutting edges of irregular outline and teeth cut similar to 
those of an ordinary milling cutter. This class of cutters can 
rarely be ground without changing their profile. A* form cutter 
may be a combination of several cutters as is the ease with gang 
mills. Formed cutterSy however, are form milling cutters so de- 
signed and backed off that they may be ground and still retain 
their original profile. Gear cutters and cutters for grooving taps, 
reamers and drills are classed as formed cutters. 

1376. Fly Cutters. A cutter having a single cutting edge 
similar to that of a boring tool, ground to any desired profile, 
and inserted in a taper shank like that of an end mill, is the 
simplest of all form-milling cutters. Such a combination is called 
a fly cutter and is adapted to such work as the making of tools 
for screw machines, gears with odd pitch teeth, and such work 
as does not warrant the expense of a regular form cutter. 

1377. Inserted Tooth Cutters. Owing to the expense of ma- 
terial and production, solid cutters are seldom made larger than 
S^ in diameter or wider than 6* in face. When larger cutters are 
desired they are generally built up, i.e., having tool steel blades 
or teeth inserted and clamped in a body of some inexpensive 
material in such a manner as to admit of their being easily removed 
in case of injury or wear. There are several styles of inserted 



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MILLING 



343 




Concave and Convex Cutters for 
Milling Half OrcUa. 



Formed Milling 
Cutter for Milling 
Parts of Machinery^ 




For Taps and 
Reamers. 




For Teeth in 
Gear-Wheels. 




For Grooving 

Straight-Lipped 

Twist-Drills. 




Right-Hand Cutter. 
T-Slot Cutter. 




For End-MUling, Die-Sinking and MUling Slots. 
Fio. 1375. — Formed and Form Milling Cutters. 



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344 ENGINEERING AND SHOP PRACTICE 



Fig. 1377. — Inserted Blade or Tooth Milling Cutter. 

tooth, or built-up, cutters now on the market, and many are the 
designs and devices for holding the teeth or blades. 

1378. Slitting Saws and Screw Slotters. Axial cutters whose 
width of face is less than J* are termed either slitting saws or 



Fig. 1378a. — MeUl Slitting Saw or Cutter. 

screw slotters, according to their constniction and use. Slitting 
saws are ground hollow on the sides for clearance. 



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MILUXG 345 



Fig. 13786. — Cutter for Key-seating and Slotting. 

1379. Straddle and Gang Mills. When two side-milling cut- 
ters are placed on the arbor and separated by a washer, in such 
a manner that two opposite sides of a piece may be machined at 



Fig. 1379. — a Gang Mill 

one operation, they are termed straddle mills. If, in the above 
arrangement, a face mill be used instead of the washer between 
the side mills, the combination is termed a gang mill. 



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CHAPTER XIV 

MISCELLANEOUS MACHINE TOOLS AND 
ACCESSORIES 

Presses 

141 1. Classification. The two common classes of presses with 
which the machinist is familiar are assembling and die presses. 
Assembling presses are used for assembling press or forcing fits 
and, though generally hydraulic, are sometimes operated by hand 
or power; while presses using dies for punching and stamping 
sheet metal are termed die presses. 

1412. Assembling Presses — Arbor — Hydraulic. An arbor 
press is a small hand assembling press, used chiefly for pressing 
arbors into the hubs of the various bored pieces to be turned. 

In brief, the essential parts of the hydraulic assembling press 
are: a hydraulic cylinder containing the movable ram, which latter 
does the pressing by being forced outward; a sliding head against 
which the pressing is done; tie bars which hold the sliding head, 
cylinder and ram in their relative positions; a hydratdic piimp for 
pumping the water into the cylinder; and a base with a guideway 
for supporting these details. 

1413. Die Presses. Die presses, or punching and stamping 
presses, may be hand or power machines; the hand presses are 
usually "screw presses," while the power presses are generally 
presses with a reciprocatory ram. This latter class may be 
briefly described as having the following essential parts: A base 
or legs supporting the bed or platen and the operating mechanism; 
a bolster for holding the die block; housings, carrying the guide for 
the ram and the bearing for the crank shaft; a reciprocating ram, 
in the head end of which is fitted the punch shank; and the 
operating mechanism, consisting of a crank shaft, a clutch and a 
heaiyy driving wheel. 

346 



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MISCELLANEOUS MACHINE TOOLS 347 



Fig. 14r2a. — Greenerd Arbor Press. 



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348 



ENGINEERING AND SHOP PRACTICE 



Fig. 14126. — Springfield Bench Straightening Press. 





M]^7m^mi::& 



Fi.iHi' .^'111 "'l''^:".!' ..Hv,^^!,,^^ J''!^ 4^^ ■"''^ ' 



Fio. 1412c. — 200-Ton Hydraulic Assembling Press. 



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MISCELLANEOUS MACHINE TOOLS 349 



Fig. 1413. — Bliss Inclinable Power Die Press. 



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350 ENGINEERING AND SHOP PRACTICE 

Dies and Die Making 

142 1. Dies. Dies are made plain, multiple, gang and com- 
pound as the work seems to require, and some are very costly 
and complex in construction. Dies are made of a special tool 
steel and are hardened and tempered. The die block is given 
clearance of 1° to 2°, the clearance commencing about i^ below 
the cutting edge of the die. In general, the die block is first 
finished and then the punch block laid out from, and fitted to it. 
Die making requires much skill, time and patience, as much of 
the metal is removed largely by the hand processes of chipping 
and filing, broaching and grinding, and many a fine die has been 
ruined by cracking during the process of hardening. 

1422. Die Making. Die making forms an important division 
of tool making and skilled die makers are well paid and in constant 
demand. The operations known as bending, forming — pressing 
sheet metal into a cavity of a simple form; drawing — a forming 
process of drawing the metal through rigid flat surfaces in order 
to prevent its w-rinkling on the edges; embossing — a forming 
process which leaves some design in relief on the metal; and 
curling — the forming of a hollow cylindrical ring at the end of 
a piece, are all accomplished in presses by the use of various 
shaped dies and punches. 

When used collectively, the term die refers to the die block 
and the punch; the essential parts of the die block being the 
hardened and tempered piece containing the opening or cavity, 
and termed the block; the stripper plate which strips the stock 
from the punch; the gage pin and guide strip, which hold the stock 
in its proper relation to the punch and die. The punch consists 
of the punch block of the desired shape, which does the shaping 
or cutting; the collar w^hich takes the thrust; and the shank, by 
means of which it is held in the ram. 

Turret Machines 

1431. Turret Lathes. The turret lathe is essentially a manu- 
facturing lathe and is used for the production of a large number 
of similar turned pieces. The characteristic feature of this lathe 
is the turret, designed to bring in rapid succession a numl>er of 
varieties of tools, which act on the stock passed through the 
spindle and held in the chuck. The turret, carrying the turners. 



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MISCELLANEOUS MACHINE TOOLS 351 

cutters and tools, is mounted on a slide which occupiesthe position 
of the tail-stock of the ordinary lathe; it is designed to revolve 
automatically, by the backward movement of the slide, on a 
vertical axis. After each tool has taken its cut, the slide is 
moved back; this backward movement automatically unlocks 
and revolves the turret and brings into position the tool which 
is to perform the next operation. 



Fig. 1431. — Pratt & Whitney Turret Lathe. 

Other important features of the turret lathe are the automatic 
chuck, which grips the bar of stock during the turning operations, 
and the cross-slide for cutting off operations. 

1432. Box Tools and Turners. For turret lathe work box 
tools and turners — tools having a back rest which holds the 
work up to the cutters, thus securing the desired reduction in 
diameter — are used, though the hollow mill possesses many 
advantages for this class of lathe work. Screw cutting in the 
turret lathe is effected by the use of dies; during all cutting 
operations the work is flooded with lard oil. 

It will be rightly inferred that the turret lathe must be '^set 
up*^ for each kind of piece to be produced, and that, unless small, 
similar pieces are desired, the time consumed in the *^set up" 



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352 ENGINEERING AND SHOP PRACTICE 



Fig. 14'.V2<i. — Hartncss Regular Hox Tools or Turners. 



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MISCELLANEOUS MACHINE TOOLS 353 



Fig. 14326. — Pratt & Whitney Single Turner with 
Tangent Cutter. 



Fig. 1432c. — Pratt & Whitney Single Turner with 
Radial Cutter. 



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354 ENGINEERING AND SHOP PRACTICE 



Fig. l4S2d, — Pratt & Whitney Universal Turner. 



Fig. 1432c. — Pratt & Whitney Multiple Turner with Radial Cutters. 



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MISCELLANEOUS MACHINE TOOLS 355 



Fio. 1432/. — Pratt & Whitney Multiple Turner with Tangent Cutters. 



Fig. 1432^. — Pratt & Whitney Open Side Turner. 



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356 ENGINEERING AND SHOP PRACTICE 



Fig. 1432/1. — Pratt <fe Whitney Taper Turner with Leading Back Rest. 



Fig. 1432t. — Pratt & Whitney Bell Mouth Pointing Tool. 



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MISCELLANEOUS MACHINE TOOLS 357 



Fig. 1432/. — Pratt & Whitney Bell Mouth Pointing Tool. 



Fig. 1432A;. — Pratt and Whitney End Forming and Pointing Tool. 



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358 ENGINEERING AND SHOP PRACTICE 



Fig. 1432^. — Pratt & Whitney End Forming and Point- 
ing Tool with Forming Cutter. 



Fig. 1432m. — Pratt and Whitney End Forming and 
Pointing Tool. 



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MISCELLANEOUS MACHINE TOOLS 359 



Fig. 1432n. — Pratt & Whitney Self-opening Die Head. 

makes its use expensive. However, on repetitive work the actual 
time taken to produce a single piece is so little and the cuts so 
heavy as to excite the wonder and admiration of those who are 
unfamiliar with the operations of this epoch-making lathe. 

Other well-known machine tools, that are modifications of the 
turret lathe, are: the Hartness flat turret lathe, the Gisholt lathe, 
screw machines, monitor and forming lathes. 

1433. Screw Machines. The screw machine is essentially a 
turret lathe, the cutting operations of which are performed on 
the end of a bar passed through the spindle and chuck. Screw 
machines are either hand, automatic or multiple-spindle auto- 
matic, and like turret lathes must be '^set up'' for each kind of 
piece produced. With the automatic machines all the operations 
of feeding the stock, etc., are performed automatically through 
the media of levers and cams, it being desirable that there be 
with each new shape a specially designed or adjusted cam and a 
rearrangement of the tools. A good automatic screw machine 



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360 ENGINEERING AND SHOP PRACTICE 



Fig. 1433. — Pratt & Whitney Automatic Screw Machine. 

will produce as many as a thousand simple screws in an hour; 
and such work as binding posts, knurled thumb screws and 
similar shapes is considered its legitimate product. 

1434. Monitor Lathes. Monitor lathes are used extensively 
in the manufacture of brass goods and for a great variety of 
other articles where several operations are required to finish the 
piece. This form of turret lathe is designed for finishing, from 
the rough castings, valve spindles and parts of globe and angle 



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MISCELLANEOUS MACHINE TOOLS 361 

valves. The work is usually held in an automatic chuck, which 
may be operated by a lever without stopping the machine. Many 
monitor lathes are equipped with an attachment for chasing 
screw threads. The essential parts of this device are the master 
thread, hob or leader which fits over a stud on the head-stock; 
the chaser arm, carrying a half nut to fit this hob; and the chaser 



Fig. 1434. — American Monitor Lathe. 

bar at the back of the lathe, to which this arm and the slide are 
attached. The operation of chasing threads, it will be seen, is a 
very simple one indeed. 

1435. Forming Lathes. This type of turret lathe is used 
extensively for finishing brass and other soft metal castings, and 
is a form of the monitor lathe. It embodies a departure from 
the old system of turning irregular shapes and is extremely 
simple in operation, while the quality of work is such that, for 
a certain class of work, it is rapidly superseding other machines. 
The most characteristic feature of this machine is the forming 
tool and its slide. The forming tool is a tool having a cutting 
edge, the outline of which is similar to that of the piece to be 
turned. Fastened in the cross slide it is brought up to the work, 
and by means of a lever or screw the tool is fed across or under 
the piece which, with the one movement, it turns to its proper 
shape and diameter. Oil cups, cocks, hose nozzles and similar 
shapes are produced in this machine. 



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362 ENGINEERING AND SHOP PBACTICE 




Fig. 1435a. — Garvin Forming Lathe. 



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MISCELLANEOUS I£ACHINE TOOLS 



363 




h-- 



-4' 



T 



Q 



T 

I 

i 
J.. 



^ V 






-4H^ 






k-- 






-8*- 



5'- 




FiG. 14356. — Forming Lathe Work and Slide. 

Jigs 

1441. Drilling and Filing Jigs. A jig is a device used in the 
manufacture of duplicate or interchangeable work to secure the 
accurate alignment of surfaces, parts or holes and the admeasure- 
ments of distances in such a manner as to facilitate the operation 



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364 ENGINEERING AND SHOP PRACTICE 

and eliminate the employment of skilled labor. Jigs may be 
divided, according to their use, into various classes, such as 
aligning, filing and drilling jigs. While jigs are used for lathe, 
planer and a variety of work, drill jigs — used also for reaming 
and tapping — are by far the most common type. 

1442. Jig Characteristics and Design. Though existing in a 
variety of forms and shapes, the essential parts of a jig are: The 
bodyy on or in which the work is held and which supports the 
guides; the guides or bushings for the cutting tools; the stops which 
secure the alignment of the work in reference to these guides; the 
clamping device for holding the work; and a surface on which 
the jig rests, which insures the parallelism and alignment duringthe 
cutting operation. The guides are usually hardened and ground 
steel bushings which are inserted in the jig body, the insides of 
which are made to fit the drill, reamer or tap shank; their length 
is generally twice the diameter of the hole, the end receiving the 
drill being rounded inside and out. Clamp bushings are threaded 
on the outside and are used to assist in clamping the piece in the 
jig body. 

In the design of a jig, according to John T. Usher, the spacing 
and the alignment of surfaces, holes, parts, etc., should be so 
combined as to expedite the process the jig is intended to facilitate, 
with, however, an entire absence of complication. The designer 
should always aim to make the jig in such a manner that it will 
require no effort whatever on the part of the operator to perform 
the work the jig has to be used upon. So successfully have these 
objects been accomplished in modern practice, that, by the use 
of jigs skilled labor has been entirely dispensed with in many 
instances, and in other instances, with skilled help the production 
has been increased to a surprising extent. 

1443. Templets. Templets are used in the machine shops 
and also in the blacksmith and boiler shops to facilitate laying 
out operations. They are generally made of sheet metal and 
locate the centers and outlines which may be scribed from them. 
A templet should be so arranged as to be used for laying out as 
many surfaces and points as can be practically covered by a 
single templet and, when possible, it should be made with a view 
to using it as a test gage after the various operations have been 
performed. 



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CHAPTER XV 

SHOP PROCESSES AND KINKS 

Methods of Working Iron and Steel 

151 1. Annealing — Ordinary — Dry — Water. Annealing 
may be defined as the process of restoring to normal condition 
iron and steel that have been unevenly worked, the uneven 
working producing internal strains and non-uniformity of struc- 
ture. 

Ordinary annealing may be done by heating the piece to a 
cherry red and allowing it to cool slowly to black heat. Cutting 
tools may be annealed in this manner before hardening. 

Dry annealing is accomplished by heating the piece to a 
medium red and packing it in hot ashes, hot sand or powdered 
air-slacked lime, then allowing it to cool slowly. 

Water annealing is accomplished by heating the steel to a 
dull red, allowing it to come almost to a black heat in hot ashes 
and then quenching it in water, brine or strong soap suds. 

1512. Quenching Baths — Brine — Zinc Chloride Solution — 
Mercury. It is a well established fact that the hardening of 
steel depends primarily on the rapidity with which heat is ex- 
tracted from it; and, secondarily on the temperature range 
through which it is cooled. Brine, since it has a much greater 
conductivity than water, will abstract heat much more quickly 
from articles quenched in it; thus a greater degree of hardness 
may be obtained by quenching from a given heat. 

Steel may be made very hard indeed by quenching, from a 
cherry-red, in a neutral solution of zinc chloride. 

Mercury, being a good conductor of heat, forms an excellent 
quenching bath. 

1513. Tempering — Air, Oil, etc. As an introduction to 
tempering, the reader is referred to Sections 275, 276 and 277 
where the subject is treated at some length. 

Blades and thin pieces of steel are sometimes tempered by 

365 



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366 ENGINEERING AND SHOP PRACTICE 

quenching them in a cold blast of air. The elasticity of Damas- 
cus blades is said to have been due to their having been air-tem- 
pered. 

Oil is used to temper springs and tools having great elasticity; 
linseed is the best oil for this purpose. Quenching in oil does 
not chill the piece as does quenching in water, and the fumes 
from the oil surrounding it possess a higher temperature than 
the steam would have, with the result that the hardened tool is 
less brittle and more elastic than when treated otherwise. 

Linseed oil ignites at 600^; consequently, if a hardened spring 
be covered with oil and the latter burned off, the resultant temper 
will be equivalent to that obtained from a temperature of nearly 
600°. 

Baths of air, lead, sand and oil heated to the proper tempera- 
ture are often used for drawing the temper of hardened pieces. 
This is the scientific method of securing uniformity in the pro- 
duct for all pieces are cooled through the same temperature 
range, i.e., from the critical point to the temperature of the 
bath. 

1514. Case-hardening and Other Processes. For informa- 
tion relative to case-hardening and the other processes and 
treatments of iron and steel, the reader is referred to Chapter II, 
in which additional matter may be found. Case hardening is 
treated in Sec. 234. 

Coloring Iron and Steel 

152 1. Preparatory Processes. In coloring iron or steel the 
following precautions are necessary to insure success: 

The pieces to be colored should be finished and polished, the 
brilliancy of the color depending upon the finish. 

The pieces should be scrupulously clean and free from oil. 

If the color be an oxide, obtained by heating, the material in 
which the piece is placed should be heated uniformly throughout, 
and be just* hot enough to char a dry, soft, pine stick. 

Hardened pieces cannot be colored by a process of heating 
without having the temper drawn. 

1522. Bluing. A simple method of bluing the finished or 
polished surfaces of iron or steel is to place, and allow them to 
remain, in hot sand, powdered charcoal or wood ashes until the 
desired color is obtained. Sand and wood ashes are used to 



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SHOP PROCESSES AND KINKS 367 

obtain the light blues, the dark blues being obtained with pow- 
dered charcoal. 

1523. Blacking. If a mixture of ten parts of potassium 
nitrate (saltpeter, KNO,) and one part of black oxide of manga- 
nese (MnOj) be substituted for the heating material in the above 
process, a deep, lustrous black will result. 

1524. ChemicaUy Obtained Browns and Blacks. This process 
consists of coating the pieces with a solution, by weight, made by 
dissolving one part of corrosive sublimate (HgClj, mercury bi- 
chloride) in a mixture consisting of sixteen parts of alcohol and 
sixteen parts of sweet niter (NO.OCjHj). The piece should be 
scrupulously clean and free from grease. The best results are 
obtained when the cleaning is effected by using first wet and then 
dry lime and taking care not to touch the articles with the fin- 
gers. After the solution has been applied with a sponge, the 
articles are allowed to remain from eight to forty-eight hours in 
a dark place, until a dry rust has formed upon them. A file 
card, free from grease, is used to remove this dry rust and to 
uncover the color; if the color is too light, the piece is again 
coated and the process repeated. 

If a piece so treated be a dark brown, and be immersed for a 
few minutes in boiling water, then coated with oil while still dry 
and hot, the color will be changed to black. Gun barrels are 
colored by this, or modifications of this, process. 

Cleaning Castings and Forgings 

1531. Pickling. The surfaces of castings, drop forgings and 
many other materials may be cleaned of sand and other dirt by 
a process known as pickling. The castings are washed with, or 
placed in, a solution of one part commercial sulphuric acid 
(H2SO4) to from four to ten parts of water; after the acid has 
had time to act — ten to fifteen minutes — they are washed with 
clean water and cleaned with wire brushes or old files. Badly 
scaled wrought iron may be pickled in a solution of one part of 
hydrochloric acid (HCl) to ten parts of water. Brass castings are 
pickled in a solution of one part of nitric acid (HNO3) to five 
parts of water. After pickling, the pieces should be thoroughly 
washed to remove all traces of the acid. 

1532. Removing Grease and Dirt. Boiling or washing in hot 
soda forms a convenient and ready method for remoxing grease. 



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368 ENGINEERING AND SHOP PRACTICE 

grit and dirt from small machine parts. The solution is composed 
of one part sodium carbonate (NajCOj, sal soda) to twenty parts 
of water. 

1533. Use of Compressed Air. Where compressed air is had, 
a hose with a nozzle connected to the system will be found an 
excellent method for removing dirt and chips from holes and 
castings. 

Soldering, Sweating, Brazing and Ferro-Fixing 

1541. Terms Defined. Soldering, brazing or sweating is, 
according to the manner in which it is done, the process of uniting 
two pieces by covering their surfaces with a molten metal. Ferro- 
fixing defines the process of brazing castings and other metals by 
the use of a compound called Ferrofix. 

1542. Soldering. Soft solder is a fusible alloy of lead and tin, 
while hard solder (spelter) is an alloy of copper and zinc or of 
copper, silver and zinc. The soldering iron or bit is generally 
used to apply and spread the metal. It consists of a pointed 
piece of copper, fastened to an iron rod which has a wooden 
handle. The joints to be soldered should be thoroughly cleaned, 
by scraping or filing, before the flux is applied, the kind of flux 
depending upon the kind of metal. Resin is used on tinned iron, 
commonly called tin; resin and tallow on lead; borax on iron; 
and salammoniac (ammonium chloride, NH4CI) on copper or brass. 
An excellent all-round flux is a fluid obtained by dissolving chips 
of zinc in a 50% solution of dilute hydrochloric acid. By adding 
to this solution one part, by weight, of ammonium chloride (sal- 
ammoniac) to eight parts of the fluid, this flux will answer for 
iron and steel. 

1543. Sweating. When such pieces as half-boxes and bear- 
ings are united by solder for the operation of boring, the process 
is termed sweating. The surfaces to be united are cleaned, 
treated with a flux and tinned — heated until a greenish tinge 
appears, then coated with solder — after which the surfaces are 
pressed together and heated until the solder melts, when they 
are allowed to cool. 

1544. Brazing. Brazing is accomplished by placing, between 
the pieces to be joined, a piece of spelter (hard solder) and fusing 
it while the pieces are held or clamped in position. The joint 
should be thoroughly cleaned and scraped before the flux is 



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SHOP PROCESSES AND KINKS 369 

applied; the fusing of the spelter is accomplished, either by means 
of a blow-pipe, or by red-hot tongs which also clamp the pieces 
in position. 

1545- Ferro-fixing. The process of brazing cast iron, long 
considered impossible, is now rendered commercially possible by 
the use of Ferrofix, a brazing compound invented by a German 
named Pich. Not only is this compound available for brazing 
broken cast iron, making it, it is claimed, stronger than new, but 
Mr. Pich has also succeeded in brazing broken wrought and 
malleable iron; cast iron to steel; wrought iron to cast; malleable 
iron to steel; and brass to each of these. The novelty of this 
process is entirely in the use of a coating of Ferrofix, applied to 
the surfaces to be united. The rest of the operation is performed 
in essentially the same manner as are the ordinary processes of 
brazing and sweating which have been briefly described. 

Miscellaneous Kinks 

1551. Forging Square Holes. A square hole may be easily 
forged in the end of a bar by first drilling into it a hole whose 
circumference equals the perimeter of the square desired and, 
after heating, hammering the piece until the hole is square. 

1552. Dividing in the Lathe. This may be accomplished by 
using the teeth in the driving gear as a makeshift for the holes in 
an index plate. 

1553. Rust Joints. An excellent mixture for filling up cracks 
or blow-holes in castings, or for cementing iron joints, is composed 
of one part, by weight, of salammoniac (NH4CI) to forty or sixty 
parts of cast-iron borings, together with enough water to form 
a thick paste; this is rammed into the joint and allowed to set. 



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CHAPTER XVI 

MECHANICS 
Fundamental Principles 

1611. Work. That we may not become confused in our 
terms, it is necessary to have a clear conception of the fundamental 
mechanical principles and definitions. 

The common unit of work is the foot-pound, which may be 
defined as that amount of work performed when a weight of one 
pound is raised a height of one foot. The unit adopted by physi- 
cists is the erg, which is the amount of work done by a force of 
one dyne acting through the distance of one centimeter. The 
following relation or equation .is one of the fundamental ones. 
Force X the distance through which it acts, always equals the 
resistance X the distance through which it is made to act; that is, 
FD — rd. Here we see that in the performance of work force 
and motion are of equal importance; and that a given amount of 
work may either be performed by a large force with slight move- 
ment or a small force with great movement. As an example, our 
idea of a 1500 horse-power engine is a machine of great size; 
however, it is not uncommon for the two small engines of our 
compound locomotives to develop this amount of power. 

1612. Power. Power is the rate of doing work and is a pro- 
duct whose factors are space, time and force. A complete idea 
of the power of a prime mover, such as the steam engine, being 
formed when we say that it performs so many foot-pounds of 
work in one minute. Watt, in his anxiety to have his engines 
develop their rated capacity, took as the value of the horse-power 
a quantity nearly double what the average horse can develop 
while walking — 17,600 foot-pounds per minute — selecting the 
value 33,000 foot-pounds per minute. This unit of power is the 
one in common use in steam engineering. The unit of electrical 
power is the watt or kilowatt (one thousand watts), 746 watts 
being equivalent to one horse-power. 

370 



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MECHANICS 371 



Heat 



162 1. Theory. Heat is generally considered to be molec- 
ular kinetic energy, or rather the kinetic energy of ultimate 
particles of matter. That is, that energy which is due to the 
motions of the ultimate particles of the body under consideration, 
as distinguished from the term "molar kinetic energy," which is 
kinetic energy due to the motion of the body as a whole, indepen- 
dent of the individual relative motions of its component particles. 

The particles composing a lx)dy do not come into this condi- 
tion of motion spontaneously: such energy may come from some 
source outside the body, or it may l)e received by the particles 
on account of some chemical change taking place within the 
body itself. In any case, however, the particles must receive the 
energy from some source outside themselves. A rise of tempera- 
ture is the usual manifestation which takes place from such a 
transference or transformation of energy, and a definite relation 
exists between the work (Force X Distance or J Mass X Velocity') 
which disappears and the temperature rise which ensues in any 
given body. 

1622. Relation between Heat and Work. Count Rumford 
was among the first to conceive the idea that heat is a mode of 
motion and is produced by the expenditure of work; basing this 
theory upon his observation of the large amount of heat produced 
in the process of boring cannons. It is a fact that in most cases 
energy expended in friction is entirely converted into heat. 
TyndalPs experiment of producing steam — the steam blowing a 
cork from the end of a tulje — directly from the heat of friction 
illustrates the truth of this statement and exhibits the trans- 
ference of the work of friction into heat energy, and of the heat 
energy in the steam into the work of motion in the cork. 

In 1849 Dr. Joule devised an apparatus by which he was able 
to determine that the same relation always exists between a unit 
of work and a unit of heat. This was called the mechanical 
equivalent of heat; the unit of heat in the British system of units 
being that quantity required to raise the temperature of one pound 
of water one degree F. at the temperature of maximum density 
which is 39.2° F. or 4° C. The foot-pound previously defined as 
the unit of work is that amount necessary to raise one pound 
weight Avoirdupois vertically one foot. This mechanical equiv- 



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372 



ENGINEERING AND SHOP PRACTICE 



alent of heat Joule determined to be 772.6 foot-pounds, while 
Professor Rowland's more exhaustive researches showed it to be 
778 foot-pounds. 

1623. An Experiment in Thermodynamics. Let us now con- 
sider the processes in the following experiment: The apparatus 
consists of a cylinder with a tightly fitting weightless, frictionless 
piston, and some method of heating the cylinder. A pound of 
water at 32® F. is placed in the cylinder underneath the piston. 
The first effect of the application of heat is to raise the temperature 
of the water which expands inappreciably. Beginning with the 
boiling of the water, the second effect is that of the formation of 
steam which forces the piston out. At the instant evaporation is 
complete as well as during all the time it is going on the cylinder 
is said to contain saturated steam; that is, steam which contains 
just exactly enough heat to maintain it in the gaseous form, and 
no more. The continued application of heat after evaporation 
has been completed results in the moving of the piston still farther, 
and the steam in the cylinder which has become considerably 
hotter — that is, contains more heat than is necessary to keep it 
in the gaseous form — is said to be superheated. 

At the instant when all the water has been changed to steam, 
the piston will have been moved such a distance in the cylinder 
as will indicate that the volume of steam has increased 1646 
times that of the water. 

If we were to measure the number of heat units applied at 
the instant when the last drop of water was evaporated, we would 
discover that 180.9° were used to heat the water and 965.7° to 
effect a molecular change from water to steam, making the total 
heat units of steam at 212° to be 1146.6. If now we should 
arrange a table (Fig. 1623) setting down therein additional heat 
in pounds of steam at certain pressures and the differences, we 
would discover that with small additions of heat the pressure 
rises rapidly. 



Absolute Pressure 


Total Heat Units 
.Above 32 Deg. 


Additional Heat Units 
per Pound of Steam 


Differences 


14.7 Lbs. 


1146.6 






25 " 
75 " 


1155.1 
1175.7 


8.5 
29.1 


20.6 


125 " 
175 " 

225 '' 


1186.9 
1194.9 
1201.4 


40.3 

48.4 
54.8 


11.2 
8.1 
6.4 



Fig. 1623. 



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MECHANICS 373 

From the above table we are impressed with the facts: (1) 
That so small a portion of the heat is converted into useful work 
and (2) that so marked an increase in pressure occurs by the 
addition of a small number of heat units. We then conclude this 
to be a wasteful method of using steam. Experience has proved 
that any method in which the steam follows the piston at full 
pressure during the entire stroke is wasteful. This led to the 
invention of various devices for cutting off the steam at some 
point before the completion of the stroke. It is sufficiently exact 
for our purpose to say that if a given quantity of steam be ex- 
panded to twice its volume, its pressure will be one half; if to 
three times its volume, its pressure will be one third. 

Power Graphs and Computations 

163 1, The Indicator Card. On a graph representing pressures 
and volumes, the expansion curve will be an hyperbola and the 
area of the graph will represent the amount of work done. If 
steam be cut oflF at some portion of the stroke, the pressure upon 
the piston, it will be seen, is far from uniform and the speed of 
the piston is variable. In our computations of the work per- 
formed it will be necessary, then, to use average pressures and 
speeds; average pressures and speeds being those which produce 
the same total eflfect as variable ones. 

In the following graph (Fig. 1631), where FD represents 
length of stroke and FA maximum pressure, the steam is cut off 
at one quarter of the stroke and expands to a minimum pressure 
of DC. 

The area then of the graph may be taken as being propor- 
tional to the total work done by the steam. It is apparent that 
the economy of using expanding steam is great, as a glance reveals 
the area BCDE to exceed that of ABE F, If the area of ABE F 
be 1, it can be proven that the area of BCDE equals the hyper- 
bolic logarithm of the ratio of expansion. The ratio in this 
instance is 4; the hyperbolic logarithm for 4 is 1.386, so that the 
total area of the figure representing the total work done by the 
steam is 2.386. If we had allowed the steam to follow the piston 
during the entire stroke, the area of the graph would have 
been 4, but four times the amount of steam would have been 
used. 



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374 ENGINEERING AND SHOP PRACTICE 



Fig. 1631. — Indicator Card. 

1632. Power and Steam Computations. A computation of 
the steam used in each of the two instances will serve to illustrate 
the economy in another way. Let the area of the piston be 
200 square inches, the revolutions 60 per minute, and the length 
of stroke 2 feet (two strokes always per revolution); then the 
foot-pounds of work developed per minute for the case when 
following full stroke are 

Sq. in. Lbs. Ft. Revolutions Foot-pounds 

(200) X (100) X (4) X (60) equals 4,800,000: the horse power 

4 SrM) 000 
being the foot-pounds divided by 33,000 or-'- -'— equals 145.4 

horse- power. 

The numljer of cubic feet of steam used per hour is 

Sq. Ft. Feet Revolutions Minutes 

(144^ ^ ^^^ ^ ^^^^ ^ ^^^ ®^^*^^^ 20,000 cubic feet. 

The weight of a cubic foot of steam at 100 pounds absolute 
is 0.23 pounds and the steam consumed per hour is 0.23 x 20,000 
or 4600 pounds. The steam used per horse-power per hour is 

■ . ■ equals 31.5 pounds of steam. Computing the steam used 
when cutting off at J the stroke, we have: the average height of 



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MECHANICS 375 

the figure or mean effective pressure '^^~~ ^^}^^^^ -^^ ^^ ^^® 

height or pressure due to 100 pounds. The average pressure is 
100 X .596 e(iuals 59.6 pounds. The work equals 200 X 59.6 X 

4 X 60 equals 2,860,800 foot-pounds. ^'^^^^^ equals 86.6, the 

horse-power. The steam used per hour equals \ quantity in 
first case or 1150 pounds; hence the quantity per horse-power 

per hour is ^^V equals 13.2, which is less than one half that used 

when following full stroke. 

Owing to the fact that there are many losses due to back 
pressure, clearance, friction of the steam in passage and conden- 
sation, this amount of economy is seldom mot with in actual 
practice. 



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CHAPTER XVII 

POWER-GENERATING MACHINES 

Steam Engines and Turbines 

1711. The Steam Engine. Steam engines may be divided 
according to the number and arrangement of their cylinders into 
simple, compound, triple-expansion, quadruple-expansion, duplex, 
etc.; according to the type of valve and valve gearing used, into 
plain slide valve, piston valve, automatic cut-off, Corliss, etc.; 
and according to their use, into stationary, locomotive and marine. 
Any of the above may be either single or double acting as the 
steam is admitted to one or both sides of the piston; horizontal 
or vertical as the center line of the engine cylinder is horizontal 
or vertical; and condensing or non-condensing when exhausting 
into a partial vacuum or into the atmosphere. 

The details of the simple slide-valve engine are so well known 
that an enumeration of their names and functions would almost 
seem superfluous. However, the following figure (Fig, 1711) with 
lettered details may prove of service to the novice. 

The cut represents a typical vertical piston valve engine as 
built by the Buffalo Forge Co., the principal parts of which are 
the cylinder, Cyly in which reciprocates the piston, P. The 
reciprocating motion of the piston is transformed into the rotary 
motion of the shaft through the piston rod, PR, the cross-head, 
C Hy the connecting rod, C/2, and the cranks, C. To the shaft is 
attached the eccentric, E, by means of which motion is given to 
the valve F, and the fly-wheels W which serve the double purpose 
of steadying the rate of rotation and of transmitting the power. 
The fly-wheel nearest the eccentric contains the governor, (?, 
which by shifting regulates the amount of steam at any stroke. 

The movement of the valve across the ports,* p, is effected by 
the eccentric, through the eccentric rod, ER, the slide, S, and the 
valve rod, VR, to the valve. The relative position of the crank 
and eccentric is "quartering"; that is to say, that when the piston 

376 



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POWER GENERATING MACHINES 



377 



reaches the end of its stroke the valve has reached the middle of 
its stroke. Steam enters the steam chest, SC, through the steam- 
pipe and fills the space X between the two portions of the valve. 
The passage of the steam is as follows: With the piston at the 




Fig. 1711. — Section of a Vertical Piston Valve Engine. 

bottom of the cylinder as indicated, the valve moves downward, 
uncovering the lower port and admitting steam underneath the 
piston, forcing it up and causing the steam above it to be ex- 
hausted through the upper port, which latter is open to the 
atmosphere. By this time the valve has moved upward so as 
to admit steam through the upper port, thus forcing the piston 



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378 ENGINEERING AND SHOP PRACTICE 

down to its original position, compelling the steam which forced 
the piston up to be exhausted through the lower port. This 
action is continuous and automatic. 

1712. Turbines. A steam turbine generally consists of a disc 
or cylinder with properly formed buckets or blades on the circum- 
ference, against which the steam impinges at a determined angle. 
In its simplest form it is a turbine wheel operated by steam 
instead of by water as is the ordinary turbine. 

The most important reason for the high efficiency of the 
turbine is that it is adapted to use effectively the highest possible 
degrees of expansion; while in the reciprocating engine it is prac- 
tically impossible to provide for high degrees of expansion. As 
the exhaust pressure approaches a perfect vacuum, the volume 
naturally increases at a rapid rate — the volume of steam with 
a 29-inch vacuum being double that with a 28-inch vacuum. In 
the turbine the highest degree of expansion is easily provided for 
because of its immense advantage in the use of a very high vacuum 
and all degrees of superheat. Consequently a much larger portion 
of the heat (work) in steam can be utilized by turbines than by 
steam engines. 

The respective weights of complete generating units exclusive 
of foundations — reciprocating engine and turbine — are in the 
ratio of 8 to 1, and the saving in foundations alone is a very 
important item. 

The important steam turbines on the market are the Dow 
and the Pyle, the DeLaval, the Curtis and the Wcstinghouse- 
Parsons. The Dow and the Pyle have their chief use in loco- 
motive head-light work. The DeLaval is very efficient and is 
built in sizes up to 3(X) horse-power, while the Curtis has its chief 
use in direct-connected generator work, generally in large plants, 
and is built in units up to 5000 kilowatts. The Westinghouse- 
Parsons is built in larger sizes than any other, the largest on the 
market being 10,000 kilowatts or 15,000 horse-power. It is used 
extensively for both marine and electrical generating work. 

1713. The Dow and Pyle Turbines. The Dow turbine is a 
series of radial outward-flow turl)ines placed like a series of con- 
centric rings in a single plane with a stationary guide ring between 
each pair of movable rings. 

'The Pyle turbine is similar to the Dow, with the exception 
that it consists of inward-flow turbines. These two types of 



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POWER GENERATING MACHINES 379 

turbines are extensively used for small self-contained generating 
plants on locomotives for electric head-light work. 

1714. The DeLaval Turbine. In the DeLaval turbine the 
steam enters a ring-shaped chamber surrounding the casing of 



FiQ. 1714a. — Action of Steam in DeLaval Turbine. 



Fig. 17146. — DeLaval 200 K. W. Twin Generator Set. 

the turbine and from this it enters several nozzles that convey 
the steam to the turbine buckets, which are fastened to the cir- 
cumference of a single disc. A steam jet is directed by these 



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380 ENGINEERING AND SHOP PRACTICE 

nozzles against the plane of the turbine at quite a small angle, 
and tangentially against the medium circumference or center line 
of the buckets. The interior of these nozzles is tapered with the 
large end toward the buckets, and the steam in passing through 
the nozzle, expanding freely to the pressure of the surroundings, 
acquires great velocity. The energy due to this velocity is 
imparted by impact to the buckets, thereby rotating the wheel. 

Kent makes the following remarks in reference to the DeLaval 
steam turbine: "As the steam passes through the channel or 
nozzle, its specific volume is increased in a greater proportion 
than the cross-section of the channel, and for this reason its 



Fig. 1714c. — Sectional Plan of DeLaval Turbine Dynamo. 

velocity is increased and also its momentum, till the end of the 
expansion at the last sectional area of the nozzle. The greater 
the expansion in the nozzle, the greater its velocity at this point." 
Expansion is carried further in this steam tiu-bine than in ordinary 
steam engines. He further states that to obtain the best possible 
effect, the admission to the blades must be free from blows and 
the velocity of discharge as low as possible. These conditions 
would require in the steam turbine an enormous velocity of the 
periphery, as high as 1300 to 1600 feet per second. On account 
of centrifugal force, the velocity of the periphery of a 5 horse- 
power turbine is .574 foot per second, the number of revolutions 
being 30,000 per minute. 

The inability to secure a coincidence of the center of gravity 
and the geometrical axis of revolution, on account of the uneven- 
ness in the texture of the material, necessitates such provisions 



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POWER GENERATING MACHINES 381 

and adjustments as will allow the rotating mass to adjust its 
center of rotation to its center of gravity. This is generally 
accomplished by the use of a flexible shaft, movable bearings, or 
the use of a bearing which is kept filled with oil at a very high 
pressure. 

As will be seen from Fig. 1714c the speed reduction necessary 
for ordinary purposes is effected by means of the gearing J K, 
This type of turbine is built in units up to 300 horse-power. 

1715. The Curtis Turbine. In the Curtis turbine no attempt 
is made to keep the speed of the vanes up to one half that of the 
jet — this is a condition of economy in the DeLaval — for it is 

Steam Chest 



ule 

KOTlng Bladen 
Stationary Blades 
SIOTing Blades 
Statlonar J Blades 
Moving Blades 
\ \ 



.1 I 1 1 I I 

Fia. 1715a. — Diagram of Curtis Nozzles and Buckets. 



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POWER GENERATING MACHINES 383 

not sought to take all the velocity out of the jet in the first bucket. 
What remains after the first bucket is passed is not wasted but 
absorbed by the series which follows. The following description 
is taken in part from Power and from the General Electric Co.'s 
pamphlet by Mr. Emmett : 

A comparatively high initial velocity is given to the jet by 
expansion in a nozzle or set of nozzles in parallel as in the 
DeLaval, and this velocity is absorbed by successive action upon a 
series of alternately movable and stationary vanes arranged as 
in the Parsons, with this difference, that while in the Parsons 
turbine there is a sufficient difference in pressure between the 
two sides of each vane to induce the flow, and a continuous 
expansion, the successive vanes in any one stage of the Curtis 
are used simply to absorb the velocity or momentum already 
generated by expansion in the nozzle. See Fig. 1715a. When 
the initial velocity has been absorbed, motion is again generated 
by expansion in another set of nozzles of an area sufficiently 
greater than the first to allow for the increase of volume by the 
previous expansion, and the operation is repeated upon another 
and larger set of vanes. 

This process of expansion in the nozzle and subsequent ab- 
straction of velocity by successive impacts with the vanes is 
designated as a stage, of which there may be several. The 
general practice is to so divide up the steam expansion that all 
stages handle about equal parts of the total energy of the steam. 

Curtis turbines in units of 5000 kilowatts are in successful 
operation. 

1716. The Westinghouse-Parsons Turbine. The Westing- 
house-Parsons turbine is a series of parallel flow turbines mounted 
side by side on a shaft or cylinder and having in the casing a 
stationary guide ring, carrying blades or buckets between each 
turbine. 

The following is a description of the Westinghouse-Parsons 
turbine, of which P^ig. 1716a is a longitudinal section: 

Steam is shown as entering at S where a strainer Is provided, 
thence through the poppet valve F, controlled by the governor, 
to the admission port A and passes out to the left through the 
turbine blades, eventually arriving at the exhaust chamber B, 
The blades are similar to those shown in a previous figure (Fig. 
1715a), the steam passing first a set of stationary blades and im- 



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384 ENGINEERING AND SHOP PRACTICE 

pinging on the moving blades, driving them around and so on. 
The areas of the passages increase progressively in volume, cor- 
responding with the expansion of the steam. On the right of the 
steam inlet are shown revolving balance pistons P, P, Py one cor- 
responding to each of the cylinders in the turbine, which accord- 
ing to size may be 1, 2, 3 or 4 in number. The steam at A presses 
against the turbine and goes through doing work. It also presses 
in the reverse direction, but cannot pass the piston P, but at the 
same time the pressure, so far as the steam at A is concerned, is 
equal and opposite, so that the shaft is not subjected to any end 



Fig. 171Ga. — Sectional Elevation of Wcstinghouee- Parsons Turbine. 

thrust. By means of the equalizing ports or pipes E the pistons 
are subjected to the same pressure as that acting on- the various 
drums. 

The areas of these balance pistons are so arranged that no 
matter what the load may be, or what the steam pressure or 
exhaust pressure may be, the correct balance is preserved and the 
shaft has no end thrust whatever. 

At T is shown a thrust bearing which, however, has no thrust 
to take care of, but serves to maintain the correct adjustment of 
the balance pistons. 

This turbine is built in units up to 10,000 kilowatts or 15,000 
horse-power. 



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POWER GENERATING MACHINES 



385 



Fig. 17166. — 5000 K. W. Generating Units. Comparison of Space 
Occupied and Size of Foundations. Modern Engine Tjrpe Unit, and 
a Westinghouse-Parsons Turbine Type Unit of similar Rating and 
Overload Capacity. 

1717. Table of Comparative Steam and Coal Consumption. 
Comparative Steam and Coal consumption per 1 horse-power- 
hour of the various types of engines: 



Kind of Engine 



Small Engines, Simple, Non-Condensing. . . . 
Medium Engines, Simple, Non-Condensing. . 

Medium Engines, Simple, Condensing 

Compound Engines, Condensing 

Triple-Expansion Engines, Condensing 

Quadruple-Expansion Engines, Condensing. 

Brotherhood Rotary Engine 

Cycloidal Engine 

Pyle Steam Turbine 

Dow Steam Turbine 

Westinghouse-Parsons Steam Turbine 

DeLaval Steam Turbine 

Curtis Steam Turbine 



Steam 



40—50 
30—32 
25—30 
16—18 
14—15 
12—13 
40—50 

35—45 
35—45 
16—20 
14—20 
15—20 



Coal 



6—12 

4—6 

4 

2 

1.75 

1.5 

6—12 

5—7 

5—7 

2.3 

2.2 

2.3 



Fig. 1717. 



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386 ENGINEERING AND SHOP PRACTICE 

Gas, Oil and Hot Air Engines 

1721. Theory and Thermodynamics. In the chapter on 
"Mechanics" we discovered that one thermal unit of heat was 
produced by the expenditure of 778 foot-pounds of work. In a 
thermodynamical discussion of heat and work, we discover that 
the greatest amount of work which can p)ossibly be obtained from 
a heat-engine in its conversion of a given quantity of heat is: 

Work = 7^-r~ X Total Heat 
T + 460 

where T and t are the temperatures on the Fahrenheit scale 
between which the perfect heat engine is working — 460 b^ing 
absolute zero on the Fahrenheit scale. 

In the application of these two laws to the steam engine, the 
first step in the process was to increase the elasticity or pressure 
of the gas (steam) by heating it in a closed vessel. The steam 
was then passed into a cylinder and expanded, during which 
process a portion of the heat was converted into useful work, the 
residue escaping from the cylinder at a lower temperature. This 
we discovered to be a wasteful process, the best steam engine 
having a thermal efficiency of from 21% to 23%. Gas and oil 
engines seek to eliminate the waste due to the complicated appa- 
ratus for heating and increasing the pressure of the gas (steam) 
by internal combustion, that is by generating heat and pressure 
directly in the cylinder of the engine. 

1722. Beau De Rochas' Conclusions — Otto and Clerk Cycles. 
In 1862 Beau de Rochas announced the four following conditions 
to be necessary to secure the best results from an expanding gas: 
(1) The cylinder should have the greatest capacity with the 
smallest circumferential surface; that is, a cylinder whose length 
is equivalent to its diameter. (2) The speed should be as high 
as possible. (3) The cut-off should be as early as possible. (4) 
The initial pressure should be as high as possible. This postu- 
lates that ignition of the gas should take place at the dead point; 
such, however, is not the practice with modem engines, for it 
has been discovered that in this class of engines and in guns — 
in which the action of the gas is analogous — better results are 
secured where the rise of pressure is more gradual and its inten- 
sity partially sustained. Practice shows that two important 



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POWER GENERATING MACHINES 



387 



advantages are secured by so doing; first, starting is made easier, 
and second, though the area of the diagram is diminished, the 
brake power is increased. 

There are two characteristic cycles under which the greater 
portion of gas and oil engines operate: 

The Otto or four-cycle in which the following sequence of 
operations takes place every two revolutions of the fly-wheel or 
every four strokes of the piston: (1) The inspiration of the 
explosive mixture during the entire first forward stroke. (2) Its 
compression during the next or return stroke. (3) Ignition at or 
near the dead point and expansion during the next stroke. (4) 
The expulsion of the burnt gas during the fourth stroke. 



Induction - Stroke i 




Compression - Stroke a 




K 



Power- Stroke 3 



Indicator 
Card 



Cl< 
Ignition: 




Closed- 


^ 






Closed- 


f ■= 





^ 




A Exhaust - Sl 


troke .4 


1 


\ Indicator 
I \Card 

Volnino 




Open- 
Closed- 


\ I 


0-^ 


-^ 




Fio. 1722a. — Operations in Four-cycle En^nes. 




>/ 



In the Clerk or two-cycle the following sequence obtains: 
(1) The admission of the compressed explosive mixture and its 
further compression during the return stroke, and (2) the ignition, 
expansion and expulsion of the gas on the forward stroke. 

In his discussion of these two cycles, Dugald Clerk, while 
realizing the advantages of the Otto cycle, truthfully charges it 
with the production of engines which are subject to intermittent 
action and excessive forces incompatible with uniformity, dura- 
bility and ease of operation. He further states that the Ottq 
cycle requires cylinders enormously large by reason of the small 
mean effective pressure developed by the gas which operates by 



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388 ENGINEERING AND SHOP PRACTICE 

explosion rather than by combustion; and again, in cases where 
the regulation is effected by the admission of a variable quantity 
of the explosive mixture the compression is not generally a con- 
stant. 



Fig. 17226. — Otto Gas Engine. 

One of the great advantages of the Otto cycle, however, is 
that it lends itself readily to a design of engine which is at once 
simple in mechanical construction, efficient in the use of fuel and 
easily operated. 

1723. Discussion of Details and Methods of Regulation. At 
the present time, the majority of the small stationary gas and 
oil engines operate on the Otto cycle with what is called the 
''hit or miss'' system of regulation. 

The " hit or miss " system of regulation is based on the opening 
of the gas admission valve under the action of the governor, the 
air admission being independent and occurring at each cycle with 
the result that, as the load fluctuates, the number of admissions 
and explosions varies accordingly. The proportions of the mix- 
ture are regulated once for all while the compression remains a 
constant. 

For the reason that it is required simply to displace a little 
piece of metal between the stem of the admission valve and the 



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POWER GENERATING MACfflNES 389 

cam, the "hit or miss" system of regulation is one of great sensi- 
tiveness in the governor mechanism, it being subject to no reaction 
by the details which it operates. 

Small two-cycle engines are used to a considerable extent for 
launch and automobile work. In Europe the tendency of practice 
for the larger engines, those over 100 horse-power, is toward the 
Koerting type. The Koerting engine is double-acting, as are 
most steam engines; it operates on the Clerk cycle and has the 
combustible charge of gas and air delivered to, and the burnt 
gases extracted from, the cylinder by means of two auxiliary 



Fig. 1723a. — Sectional Plan of Koerting Two-cycle Gas Engine, Show- 
ing Piston, Main, and Charging Cylinders. 

cylinders — one an air, the other a gas — which serve as pumps. 
These cylinders are so proportioned that the proper combustible 
mixture is delivered to the working cylinder by the action of two 
piston valves. The engine is regulated by a throttling device 
under the control of a governor. This type of engine operates 
either on blast or producer gas and has a thermal efficiency, 
according to Professor Meyer, of 38%. It is made in horse-powers 
ranging from those in hundreds to those measured in thousands. 

Uniformity of rotation is secured in the single-cylinder engines 
only by the use of excessively large and heavy fly-wheels which 
reduce the mechanical efliiciency to 80% or 82% instead of 85% 
to 90%. In nearly all of the large gas engines, and especially 
those which operate on the Otto cycle, the manufacturers have 



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390 ENGINEERING AND SHOP PRACTICE 

endeavored to secure uniformity of turning effort by increasing 
the number of the cylinders. American practice tends toward a 
multiple cylinder, vertical four-cycle, engine, while European 
practice is toward a two-cylinder, horizontal, two-cycle engine, 
where economy of consumption is sacrificed to obtain a minimum 
number of moving parts and a uniform turning effort. 



Fig. 17236. — Westinghouse Vertical Gas Engine. 

One of the best known Americanized engines is the Diesel 
engine, manufactured at Providence, R. I., the latest type of 
which has three vertical cylindei-s mounted symmetrically and all 
driving the same shaft, each cylinder operating independently on 
the Otto cycle. 

1724. The Diesel Engine. From a description published in 
Power y April, 1903, we learn that: **The Diesel engine has three 
distinctive characteristics as compared with existing explosive 
gas and oil engines. They are (1) The content of the cylinder 
during the compression stroke is air only and the temperature 



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POWER GENERATING MACHINES 391 

due to compression is far above that which is necessary to ignite 
the combustible charge. (2) The clearance is only about 7% of 
the cylinder volume and in this space is confined, under great 
pressure, more than enough air to supply oxygen for the com- 
bustion of any amount of fuel the engine is designed to use. 



FiQ. 1724. — 750 B.II.P. Diesel Engine. 

(3) The combustion of the fuel is not an explosion, but it burns 
as fast as injected into the cylinder without increasing the pres- 
sure produced by compression. *. . . The opening of the fuel valve 
allows the compressed air — compressed by an auxiliary cylinder 
— to drive out through perforated washers the oil in the form of 
a fine spray. It is driven into the cylinder and ignited by the 



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392 ENGINEERING AND SHOP PRACTICE 

extremely high temperature of the air compressed by the up 
stroke of the piston. Any grade of crude or fuel oil may be 
used. The air which supports combustion is drawn into the 
cylinder through an automatic mushroom valve and compressed 
by the up stroke of the piston to between 450 and 525 pounds 
per square inch. The resulting temperature approaches 1000 F. 
and this is much more than sufficient to ignite the oil as soon as 
it is injected. At the commencement of the down stroke the 
fuel valve opens, remaining open about a tenth of the stroke, 
and fuel is admitted and burned — in no sense exploded — during 
the whole or part of this period, according to the action of 
the governor. After the fuel supply is stopped, the resulting 
gases of combustion work expansively during the rest of the 
stroke." 

Tests of this engine show a thermal efficiency of 41.83% and 
tests on a single-cylinder engine of this type produced a brake 
horse-power per hour on J pound of ordinary crude oil. The 
reliability of this engine is evinced by a continuous ruh of over 
two weeks in which the operation was absolutely without stop 
and the variation of electrical pressure generated was very small. 

1725. Fuels. As may b3 gathered from the foregoing text, 
and from Figs. 1725a and b on pages 394 and 395, the fuels em- 
ployed in these engines vary widely. Of the gases commonly 
used, we may mention ordinary illuminating gas, producer gas 
and the waste gases from blast furnaces. Alany gas and gaso- 
line engines operate on carbureted air, the air being passed 
over gasoline or some other volatile petroleum spirit of low 
specific gravity, is saturated with vapor and becomes equal in 
heating or lighting power to ordinary coal gas. Great caution 
should be used in the handling of gasoline, the danger arising 
because the vapors given off at ordinary temperatures are highly 
explosive. One of the defects of a common form of carbureter 
is that the more volatile oils are first taken off, leaving what is 
sometimes a useless oily residue. To obviate this difficulty some 
manufacturers spray the gasoline into a current of air by which 
it is vaporized; the mixture is then compressed and ignited by 
an electric spark. When gasoline is so used, it should be led 
from an underground tank through soldered pipes to the com- 
bustion chamber, and at no time should it come in contact with 
the air outside of the engine. There should never be any flame 



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POWER GENERATING MACHINES 393 

or burning gases in the vicinity of the cylinder, except of course, 
in the case of hot tube ignition, where it is a feature of the en- 
gine. 

Motors of the Priestman and Diesel type operate on the less 
volatile petroleum products such as kerosene, partially refined or 
even crude oil. If for no other cause than the low cost of fuel, 
the gasoline engine is rapidly superseding the small steam 
engine, for as early as 1893 the cost of fuel at retail for small 
gasoline engines was on a par with the steam engine using 6 
pounds of coal per horse-power hour, with coal at three dollars 
and one half per ton. The saving here would be the cost of 
attendance for boilers and the handling of the solid fuel and 
ashes. The cost of operation for a gasoline engine requiring 
one tenth gallon per horse-power per hour, with gasoline at eight 
cents per gallon, would be .8 cents per horse-power per hour. 

1726. Operation. Gas engines, unlike steam engines, do not 
start without the aid of some auxiliary starting device. Starting 
devices have taken various forms according to the ideas of the 
manufacturers; some of the methods employed being a crank 
turned by hand for the smaller sizes; a simple means of placing 
a starting charge in the cylinder; or the starting may be effected 
by the use of compressed air. 

The life of the ordinary gas engine is far shorter, for the 
reasons stated by Clerk, than the life of the ordinary steam 
engine of the same horse-power. However, this mechanical diffi- 
culty is being rapidly solved both in America and in Europe. 
At present this short life offsets to some degree the economy of 
the gas-engine plant. 

1727. Naphtha Engines. Naphtha engines use naphtha in the 
boiler instead of water, the vapor being used expansively in the 
engine cylinder as steam is used. Upon being exhausted it is 
condensed and returned to the boiler; a portion of the naphtha, 
however, being used as fuel under the boiler. These engines are 
used almost exclusively for small yachts and launches. A 4 
horse-power engine weighs 300 pounds, consumes from 4 to 6 
quarts of naphtha per hour and takes but about two minutes to 
get under headway. 

1728. Hot-air or Caloric Engines. Hot-air engines are used 
to some extent for pumping small quantities of water, but their 
bulk is enormous compared with their effective power. The heat 



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394 



ENGINEERING AND SHOP PRACTICE 



H 

O 
06 

H 

H 
O 



o 



< 

H 

o 
O 







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POWER GENERATING MACHINES 



395 



Constituents of Power Gases — General Properties 

Courteay Westinghouse Machine Co. 



Gas 




Heating Value 






Chem- 


B. T. U. 




Characteristics— Where Found 


Name 


ical 
Symbol 


Cu. Ft. 
Net 


Relative 




Hydrogen 


H 


278 


i 


Element formed from decomposition 
of steam (HjO) or hydrocarbon 
compounds. Bums very rapidly 
with high flame temperature. 


Oxygen 










Element, not considered a combust- 
ible as it displaces an equal amount 
of (0) in air for combustion. 


Nitrogen 


N 







Element. Inert gas entering with 
air (N-79%, 0-21%). Retards 
speed of combustion. 


Carbon Mon- 










oxide or Car- 










bonic Oxide. 


CO 


326 


1.17 


Valuable constituent. Product of 
incomplete combustion (oxidation) 
of C in presence of excess carbon. 


Carbon Diox- 










ide 


COj 







Inert gas. Product of complete com- 
bustion of C. Occurs in all pro- 


















ducer and blast gases. Retards 










speed of combustion. 


Methane or 










Marsh Gas. . 


CH, 


913 


3.29 


Most valuable constituent evolved by 
natural or artificial decomposition of 
vegetable matter, coal or crude oils. 


Acetylene 


CH, 


1427 


51.4 


Higher hydrocarbons, usually as 


Ethylene or 








"illuminants" — occur in small 


Olefiant Gas 


C^H, 


1490 


53.6 


quantities in the richer gases liber- 


Ethane 


C^H, 


1615 


58.1 


ated during destructive distillation 


Benzine or 








of coal or oil — Acetylene used 


Benzol 


CeHe 


3655 


131.5 


alono for lighting. 


Carbon 


C 






C oxidizes to CO (incomplete) and 
COj (complete). (X) oxidizes to 
COj. 


Sulphur 


S 






S oxidizes to SO, forming H2SO4 










(sulphuric acid) with water. 



Fig. 17256. 



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396 ENGINEERING AND SHOP PRACTICE 

of a slowly burning fuel is applied to the piston and rejected at 
the end of the stroke. The following data are compiled from a 
test, made by Professor Robinson, of a twelve nominal horse- 
power hot-air enigne: 

"This engine gave 20.19 I.H.P. in the working cylinder and 
11.38 I.H.P. in the pump, leaving 8.81 net I.H.P. ; while th3 
effective brake H.P. was 5.9, giving a mechanical efficiency of 
67%. The consumption of coke was 3.7 pounds per brake H.P. 
per hour; while the mean effective pressure on the working pistons 
was 15.37 pounds per square inch; in the pumps it was 15.9 
pounds. The area of the working cylinders was twice that of 
the pumps. The temperature of the hot air supplied was about 
1160 degrees F., it being rejected at the end of the stroke at a 
temperature of 890 degrees F. 

Hydraulic Motors 

1731. Water Wheels. A shaft may be rotated by water in 
one of the three following ways: by weight, by impulse and by 
reaction. Very few wheels act wholly by either of these modes, 
the wheel taking this or that form as one or the other modes of 
action preponderates. 

The characteristics of water wheels are that they operate by 
the weight of the water and move with a low velocity, the velocity 
having no definite relation to the height or head of the water 
under which the wheel operates. Paddles, blades or buckets are 
fastened to a shaft or to a ''spider" in such a manner that the 
weight of the water on them rotates the wheel. The wheels are 
designated as undershot , those which receive the water below the 
center; overshot, those which receive the water at or near the top 
and running contrary to the undershot; and breast j those which 
receive the water above the center and below the top and rim 
the same as the undershot. The efficiency of water wheels varies 
as follows, Merriam giving this efficiency: overshot wheels, 70% 
to 90%; breast wheels, 50% to 809^, with the lower values on 
the smaller wheels; undershot — with the exception of Poncilot, 
which on account of its peculiar construction has an efficiency 
of 60% — 207c to 40% . 

1732. Turbines, Theory and Discussion. The word turbine 
when used in hydraulics generally refers to an impulse or reaction 
wheel, the principle characteristic of which is that it runs with a 



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POWER GENERATING MACHINES 



397 



velocity which has a definite relation to the head under which it 
operates. In the following discussion taken in part from G. C. 
Mark's excellent work on " Hydraulic Power Engineering/' the fric- 
tion losses are neglected and the matter is presented theoretically. 

If a stream of water having a certain velocity, Vw, encounters 
a curved vane, the path of the stream will be altered, following 
the curve of the vane and leaving it in the direction which the 
vane would take were it continued. The velocity, Vw^ of the 
leaving stream will be the same as on entering the vane, the only 
change being one of direction. Should a velocity, Bv, be given 
to the vane, an inspection of the diagram will show that the water 
may never reach the vane, for when the stream has reached Vx 
the vane will have traveled to B'v. 




Vw 




Fig. 1732. 



To obviate this, either the orifice of the stream must be given 

a motion similar in direction and magnitude to fiv, or the direction 

and velocity of the stream must be altered to E, the resultant of 

Vw and Bv, The motion of the stream relative to the moving 

vane again coincides with Vw. The motion of the stream on 

leaving the vane will again coincide with vw, relatively to the 

vane, but as the vane and stream each have the velocity Bv, 

the absolute or real velocity of the stream on leaving the vane 

will be the resultant of vw and Bv or L. On entering the vane 

the stream has an absolute velocity of E and a corresponding 

WE^ 
store of energy of - — while on leaving the vane the amount was 

WU ^^ 

When L is less than E the difference has been applied to the 
vane, and may be applied in the performance of useful work. 



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398 ENGINEERING AND SHOP PRACTICE 

The velocity E of the head being fixed, the velocity L of the 
discharge should be made as low as possible, but never zero, as 
then the water would not flow from the vane. The only govern- 
ing condition for the curve of the vane is that the water flow 
gradually from the angle of entry to the angle of exit. 

J. P. Frizell points out, in a discussion more particularly of 
cup-shaped vanes, that: (1) The purpose of the vanes or floats 
in an impulse wheel is to effect the greatest possible chahge in 
the motion of the water. Their length need be no greater than 
is necessary to accomplish that change, and (2) it is a condition 
of highest efficiency that the water should leave the vane in a 
direction opposite to its motion and with a velocity equal to that 
of the vane at the point of exit. Where the edge of the vane is 
radial to the wheel, different parts move with different velocities, 
and the fulfilment of this condition is impossible. 

Frizell in his discussion of reaction wheels supposes the rim 
of a wheel to contain orifices which discharge the water in a direc- 
tion absolutely tangential to the wheel. The pressure within the 
wheel is assumed to be greater than the pressure without, the 
difference in pressure being represented by the head //. If A 
represents the cross-section of the stream, W the weight of a 
cubic foot of water and V equals the velocity; the best velocity 
of the circumference then is that due to the head H at which 
the water issues. In this case the absolute tangential velocity of 
the water leaving the wheel is zero, while the energy imparted to 
the wheel is 2 WAVH, or twice the energy of the water under 
the given head. This does not imply that the wheel is capable of 
yielding an efficiency of 200%, for, in order that the water may 
issue from the orifice while the wheel is in motion, it must receive 
a tangential velocity equal to that of the wheel, and to impart 
this velocity requires an expenditure of energy, WAVH. This 
and the several losses incident to motion, together with that du3 
to the deviation of the issuing stream from the direction of a 
tangent, must be deducted from. the original energy, 2 WAVH. 

1733- Turbines — Classes and Uses. The two classes of 
turbines, impulse and reaction, each contain several distinct 
types. The impulse turbines have no suction tube (see Mark's 
*' Hydraulic Power Engineering/' page 292 to 298) and the types 
are the Pelton or hurdy-gurdy w^heol, the radial outward flow, the 
radial inward flow and the axial flow. 



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POWER GENERATING MACHINES 399 

In general it may be stated that reaction turbines are better 
adapted for large volumes of water with low heads, while the 
reverse is true of the impulse turbine. 

1734. Impulse Wheels. In this class of wheels, those acting 
purely by impulse, the water issues from the orifices or nozzles 
with a velocity due to the head and impinges upon the vanes. 



Fia. 1734a. — Interior of Doble Impulse Turbine. 

which are cup-shaped and attached to the periphery of the wheel. 
The best known makes of impulse wheels are the Girard, the 
Doble and the Pelton; the latter is much used in this country 
and has a maximum efficiency of from 85% to 92%. 

1735. Reaction Wheels. " Most wheels act partly by impulse 
and partly by reaction, and in the purely reaction wheels the 
work of the water is finished when it issues from the orifice of 
discharge." (Frizell.) Reaction wheels may be operated with 
or without a suction tube and are of the following types: radial 
outward flow; radial inward flow and axial flow. The best known 



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400 ENGINEERING AND SHOP PRACTICE 




Fig. 1734b. — Doble Ellipsoidal Bucket after 14,000 Hours' Service under 
a Head of 1300 feet. 



Fig. 1734r. — Action of l)ol)lo NtH'dle Regulating Nozzle. 



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POWER GENERATING MACHINES 401 



5 



I 






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402 ENGINEERING AND SHOP PRACTICE 

reaction wheels are the Boyden wheel, which as early as 1846 
gave a net efficiency of 88%; the Swain; the American; the 
Risdon; the LeflFel and the Duplex. The maximum efficiency of 
this class of turbine is from 75% to 90%. 

The evolution of reaction wheels to this time has resulted in 
a form of wheel in which the water enters through openings 
having their longest dimensions parallel to the shaft, and leaves 
it through openings which have their longest dimensions radial 
to the shaft. The greatest difference between the various makes 
of wheels is mainly one of detail, either in the adaptation of the 
wheel to a horizontal shaft, in the shaft of the guides or vanes, 
in the gates and in the governing mechanism. 



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CHAPTER XVIII 

ELEMENTARY ELECTRICITY 
Nomenclature 

1811. Standards, Laws and Facts. Force, That which 
tends to produce, alter or destroy motion is called force. There 
are two units of force, the pound and the dyne. 

Dyne. That force which, acting on a mass of one gram for 
one second, will produce a velocity of one centimeter per second, 
is called a dyne. 

Work. Work, as we have learned, is the production of motion 
against resistance, and its units are the foot-pound, the erg and 
the Joule. 

Erg, That amount of work performed by a force of one dyne 
acting through a space of one centimeter is called an erg. The 
Joule is equivalent to 10,000,000 (10)' ergs; this larger imit is 
much used. 

Energy — which is the capacity to do work — is of two kinds, 
kinetic and potential. Kinetic energy is that capacity to do 
work which a body possesses by virtue of its motion. Potential 
energy is that capacity to do work which a body possesses by 
virtue of its position; i.e., that due to the separation or disar- 
rangement of attracting particles or masses. 

Kinetic energy equals - — where W is the weight of the body, 

V its velocity and g the attraction due to gravity. 

Potential energy is measured by the amount of work required 
to put the body into its position or strained condition. 

Power J whose units are the watt and the horse-power, is, as 
we have learned, the rate of doing work. 

WaU, P, the performance of 10,000,000 (10)' ergs per second is 
termed a watt, or a watt is the power of a current of one ampere 
at a pressure of one volt; i.e., watt equals ampere X volt. 746 
watts are equivalent to one horse-power. 

403 



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404 ENGINEERING AND SHOP PRACTICE 

JovlBy Wy is the unit of energy or work (volt-coulomb); it is 
practically equivalent to the energy expended in one second by 
an ampere flowing through a resistance of one ohm. 

Am'perey /, is the unit of current strength or rate of flow and 
is equivalent to an unvarying current which, when passed through 
a solution of nitrate of silver in water in accordance with standard 
specifications, deposits silver at the rate of .001118 grams per 
second. 

VoUj Ej is the unit of electro-motive force, the difference of 
potential or electrical pressure; and is that electro-motive force, 
which, steadily applied to a conductor whose resistance is one 
ohm, will produce a current of one ampere. 

Ohm^ Rf is the unit of resistance and is the resistance offered 
to an unvarying electric current by a column of mercury at 
32 degrees F., having a constant cross-sectional area, a weight 
of 14.4521 grams and a length of 106.3 centimeters. 

Coulomb^ Q, is the unit of quantity (ampere second) and is 
the amount of electricity transferred by a current of one ampere 
in one second. 

The Ampere Hour, Q', is equivalent to 3600 coulombs. 

Farad, K, the unit of capacity, is the capacity of a condenser 
charged to a potential of one volt by one coulomb of electricity. 

Henry, L, the unit of induction, is the inductance of a circuit 
when the electro-motive force induced in the circuit is one volt, 
while the inducing current varies at the rate of one ampere per 
second. 

Time, T, = one hour; t = one second. 

The following formulas and their combinations express the 
relation between the above units; they are those in common use: 

W=IEt = ^ = PRt=Pt. E^IR, i2=f , P=^=PR=^=Qf. 

K 1 It t t 

i8i2. Anologies between the Flow of Water and Electricity. 

In order to obtain a better understanding of the subject with the 
least expenditure of words, the following table of anologies, com- 
piled from Kent and Supleej is used: . 



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ELEMENTARY ELECTRICITY 



405 



ANALOGIES BETWEEN THE FLOW OF WATER AND 
ELECTRICITY 



Water 

Head, difference of level in feet. Dif- 
ference of pressure, lbs. per square 
inch. 

Resistance of pipes, apertures, etc., 
increases with length of pipe, with 
contractions, roughness, etc.; de- 
creases with increase of sectional 
area expressed by complex formu- 
las. ^ 



ELECTTRiaTY 

Volts; electro-motive force; difference 
of potential or of pressure; E or 
E. M. F. 



Ohms, resistance, R increases directly 
as the length of the conductor or 
wire, and inversely as its sectional 
area, /2 oo Z ■^ «, or in the form of 
an equation 

a constant K X length 
cross-section 

It varies with the nature of the 
conductor. Conductivity is the 
reciprocal of specific resistance. 



R^' 



Rate of flow, as cubic feet per sec- 
ond, gallons per minute, etc., or 
volume divided by the time. In 
the mining regions sometimes ex- 
pressed in ** Miner's Inches." 

Quantity usually measured in cubic 
feet or gallons, but is also equiv- 
alent to rate of flow X time, as 
cubic feet per second for so many 
hours. 

Work or energy measured in foot- 
pounds; product of weight of fall- 
ing water into height of fall: in 
pumping, product of quantity in 
cubic feet into the pressure in lbs., 
per square ft., against which the 
water is pumped. 



Power, rate of work, horse-power = 
ft. lbs. of work in one minute -j- 
33000. In water flowing in pipes, 
rate of flow in cu. ft. per second 
times resistance to the flow in lbs. 
per square foot -4- 550; in falling 
water, lbs. falling in 1 second -^ 150. 



Amperes; current; current strength; 
intensity of current; rate of flow; 
1 ampere = 1 coulomb par second. 



IR 



Coulomb, unit of quantity, Q »= rate 
of flow X time, as ampere-seconds. 
1 ampere-hour — 3600 coulombs. 



Joule, volt-coulomb; TT, the unit of 
work = product of quantity by the 
electro -motive force = volt -am- 
pere-second. 1 Joule = .7373 ft. lbs. 
If / (amperes) = rate of flow and 
E (volts) = difference of pressure 
between two points in a circuit, 
energy expended = lEt = PRt. 

Watt, unit of power, P, = volts X 
amperes «« current or rate of flow X 
difference of potential. 1 watt — 
.7373 ft. lbs. per second = 7H of 
a horse-power. 



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406 



ENGINEERING AND SHOP PRACTICE 



In the mechanical applications of electricity, it must always 

be remembered that the volt corresponds to pressure and the 

ampere to flow, and the product — the volt-ampere — is the watt, 

the unit of power, 746 of which are equal to a horse-power. The 

1000 
kilowatt equals 1000 watts, is equal to = 1.34 horse-power. 

The British Board of Trade Unit is equal to 1 kilowatt hour. 

1813. Electric Circuits. A circuit is composed of a conductor 
or several conductors joined together, and is the path through 
which a current flows from a given starting point, around the 
conducting path and back to the point again. When some of 
the conducting elements are disconnected, the circuit is termed 
open or broken in contrast to being closed or completed. A circuit 
is said to be grounded when some of the conductors have come in 
contact with the ground, either themselves or through some ex- 



+ 










< 


)» 0* ()3 < 


)* 







Fia. 1813. — A Divided Circuit. 

ternal conductor. With dynamo electric machines the terms 
external and internal circuits are used; the former to indicate 
that part of the circuit which is outside the electric source; the 
latter, that part of the circuit which is included within the electric 
source. 

A divided circuit is one divided into two or more branches, 
each branch taken separately being termed a shunt. A divided 
circuit may be shown as follows: 

1, 2, 3 and 4 are the branches, this circuit having 4 branches, 
any one of which, as 1, 2, 3 or 4, is called a shunt to the others. 

The term series is used to designate that sort of connection of 
conductors which allows the current to pass through each succes- 
sively. Multiple arc or parallel is the term used to designate 
that sort of connection of conductors in which all the positive 
electrodes are connected to one main positive conductor and all 
the negative electrodes to one main negative conductor. 



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ELEMENTARY ELECTRICITY 407 

E 

The expression / =» — is Ohms law, which interpreted is — 
K 

the strength of an electric current in any circuit is directly pro- 
portional to the electro-motive force developed in that circuit 
and inversely proportional to the resistance of the circuit. 

Induction and Magnetism 

1821. Historical Note. The discovery in 1832 of the fact 
that when a conductor is moved in a magnetic field an electro- 
motive force is set up in the conductor is attributed by Ganot 
to Farady alone, while other authorities attribute it to both 
Farady and Henry in 1831. This discovery is the foundation of 
all modem electrical engineering. 

1822. Magnets and MagneticLaws. Magnets are of two kinds, 
permanent and electro-magnets. Their phenomena of attraction - 
and repulsion being conventionally assumed to be due to lines of 
force which emanate from or surround the magnet. If iron fil- 
ings be placed near the poles, that is, in the field of an electro- 
magnet, they arrange themselves in concentric circles and from 
this it is assumed that the forces may be represented by closed 
curves termed loops of force. 

From the foregoing, Mr. Kent makes the following assump- 
tions concerning the loops of force and a conductive circuit: 

(1) That the lines or loops of force in a coiled conductor are 
parallel to the axis of the conductor. 

(2) That the loops of force external to the conductor are 
proportional in number to the current in the conductor, that is, 
a definite current generates a definite number of loops of force. 
These may be stated as the strength of field in proportion to the 
current. 

(3) That the radii of the loops of force are at right angles to 
the axis of the conductor. 

The magnetic force proceeding from a point is equal at all 
points on the surface of an imaginary sphere described by a given 
radius about that point. A sphere of radius 1cm has a surface 
of 4w square centimeters. If F = total field strength, expressed 
as the number of lines of force emanating from a pole containing 
M imits of magnetic matter, 

F - 47rM; Af = F 4. 4ir 



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408 ENGINEERING AND SHOP PRACTICE 

Magnetic attraction or repulsion emanating from a point 
varies inversely as the square of the distance from that point. 
The law of inverse squares, however, is not true when the mag- 
netism proceeds from a surface of appreciable extent and the 
distances are small as in dynamo-electric machines. 

1823. The Strength of Electro-magnets and Solenoids. An 
electro-magnet is made by coiling a current-carrying conductor 
around a core of soft iron. A solenoid is generally a uniformly 
wound, long, straight coil, carrying a current, the current pro- 
ducing a uniform field at its center, though in some special in- 
stances, as in some of the electrical instruments, the coil consists 
of a helix with but a single turn. In discussing the strength of 
the field Sheldon makes the following remarks: "i being the cur- 
rent and H the uniform field produced at the center, the solenoid 
may be considered as composed of magnetic shells arranged at 
equal distances from each other. It takes 4iri ergs to move a 
unit magnet pole — one that will repel an equal like pole when 
at the distance of one centimeter, with the force of one dyne — 
from one side of a shell to the other; and 4irin ergs to pass it 
through n consecutive shells of the solenoid. If these n shells 
occupy a length on the solenoid of I centimeters, then: 

Work = Force X Distance = HI = ^iri n ergs, 

and the magnetizing force, that is, the strength or intensity of the 
field in the solenoid is: 

A development of a Tractive formula, according to Foster is, 
as follows: 

If n = number of turns in the coil 
/ = amperes of current flowing 

1.257 = ^ (to reduce to C. G. S. units) 

Magneto-motive force = 1.257 X nl = F 

Magneto-motive force F 



<l> = Magnetic flux 



reluctance R 

* = '' 

^ R 

F = — ^ = (as above) 1.257 n/ 



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ELEMENTARY ELECTRICITY 



409 



All. 



* = 



1. 257 nJ 
J_ 
Ay. 
I 



"' = 1257 
If dimensions are in inches, and A is in square inches, then 

n/ = <^-i-X.3132 
Alt. 

and <^ = BA 
(B being the conventional symbol for magnetic flux density 
or magnetic inductions.) The formula for the pull or lifting 
power of an electro-magnet, in inch measure is, 

^ ,, ,. , V B'A 





X Ull ^111 puuiiuc 


'' 72,134,000 




Table or Magnetization and TRAcnoN of Electro-magnets 


B Lines per Sq. Inch 




B Lines per Sq. Inch 




6,450 


.577 


58,050 


46.72 


12,900 


2.308 


83,850 


97.47 


19,350 


5.190 


109.650 


166.6 


25,800 


9.228 


129,000 


230.8 


32,250 


14.39 








Fig. 


1823. 





Dynamos and Generators 

1831. Descriptioii of a Dynamo or Generator. A dynamo or 
generator may be defined as a machine which converts the me- 
chanical energy, generally of rotation, into electrical energy by 
means of electro-magnetic induction; electrical energy being 
delivered either in the form of an alternating or direct current. 
The electricity is not produced by the dynamo, its action being 
the generation or production of an electro-motive force causing 
the current to pass through the external circuit. In tracing the 
analogy between the flow of water and the flow of electricity 
through the internal and external circuits, we have — in the 



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410 ENGINEERING AND SHOP PRACTICE 

internal circuit the E.M.F. causes the current to flow from a 
lower to a higher potential just as water is pumped from a lower 
to a higher level; while in the external circuit, like water flowing 
from a higher to a lower level, the electricity flows from a higher 
or positive potential to a lower or negative potential. 

The essential parts of a dynamo are the field, the armature 
and the commutator or collector rings. The field is generally 
produced by electro-magnets made by winding a number of coils 
about suitable iron cores. The armature is so designed that the 
number of lines of force which thread through its loops or coils, 
from the field, will be constantly varied, resulting in the produc- 
tion of an E.M.F. ; it is composed of a number of loops or coils 
wound about an iron core. The commutator or collector rings 
are mechanical devices on a shaft for either converting or collecting 
the current generated in the armature; this current is taken off 
by means of stationary brushes in sliding contact with the com- 
mutator or rings. 

Dynamos may be classified according to the current delivered 
into alternating or direct current; according to mechanical detail 
into revolving armature with stationary field magnet; stationary 
armature and revolving field; and both stationary armature and 
field between which is revolved an iron core; the so-called inductor 
AC in which the poles are turned inward and carry two windings, 
the field and the armature with a central toothed inductor re- 
volving in such a way as to increase and decrease the number of 
lines of force in the field; and according to their winding into 
separately excited, series-wound, shunt-wound and compound- 
wound dynamos. 

1832. Principles of the Dynamo or Generator. We will now 
consider the phenomenon occurring when a loop of wire is revolved 
in a magnetic field about an axis perpendicular to the lines of 
force. 

It is evident from the principle of induction that, as the loop 
is a conductor whose sides but not ends move across the magnetic 
field, cutting the lines of force, there will be induced in it an 
E.M.F. In the simplest form of a bi-polar machine as the loop 
revolves about its axis, one side is going down while the other is 
going up, and for this reason the E.M.F.'s induced, though trav- 
versing in opposite directions, are on opposite sides of the loop, 
and therefore instead of neutralizing each other are cumulative, 



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ELEMENTARY ELECTRICITY 



411 



that is the two pressures must be added together. The lines of 
force threading through the loop during the first quarter are 
gradually decreasing at an increasing rate, and the E.M.F., being 
dependent upon the rate of change of the lines of force through it, 
reaches a maximum when the loop is in a horizontal position 
parallel to the lines of force, so that none thread through it. At 
the end of the next quarter revolution the E.M.F. has again be- 
come zero. If we connect each end of the wire loop with slip or 
collector rings, and the circuit be completed by brushes sliding 
on them, a current will flow through the system. During the 
next half of the revolution, that side of the loop that was going 
down begins to move upward and consequently the direction of 




Fig. 1832. — Principle of Dynamo. 



the induced electro-motive force will be changed, as will also the 
direction of the current through the circuit; thiLs for each revo- 
lution we find that the direction of the current has twice l)een 
changed, that the current is alternating and that our ideal 
machine is an alternator or alternating-current machine. 

1833. Commutators. If we wish to obtain a direct current 
from this device, it will \ye necessary to cut the rings into halves, 
giving two semicircular pieces, to each of which is attached one 
end of the loop; these pieces must be insulated from each other. 
We now have the commutator in its simplest form. If we place 
the brushes so that, at the instant the induced E.M.F. in the loop 
changes its direction, the brushes slide across from one segment 
of the commutator to the other, the current, while reversed in 
the loop, is left flowing in the same direction in the external 



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412 ENGINEERING AND SHOP PRACTICE 

circuit. Just at the instant of commutation, the induced E.M.F. 
is zero, as is also the current; this occurring twice every revolution. 
To obtain a practically constant current, free from these unde- 
sirable fluctuations, it will only be necessary to multiply the 
number of loops and commutator segments. The fluctuations in 
a bipolar machine having twelve loops and segments is 1.7% of 
the total E.M.F. If each of the loops of wire were given two 
tiUTis before being connected to the commutator segment, and 
the number of revolutions and the strength of field remain the 
same, twice the E.M.F. will be produced with the same number 
of commutator segments. 




Fig. 1833. — Principle of Commutators. 

1834. Armatures. As we have already learned, the armature 
is that portion of the dynamo in which the E.M.F. is induced by 
its movement in a magnetic field, and consists of the loops of 
wire with the necessary insulation, the iron core that sustains 
them and the minor connecting details. The loops of wire, or 
conductors in which the E.M.F. is generated, are termed inductors. 

Armatures are generally of three kinds, drum, ring and disc. 
The drum armature is one in which both sides of the loop of 
wire cut the lines of force. The ring consists of an annular iron 
core about which the wire is wound; the lines of force emanating 
from the north pole of the magnet flowing through the core 
instead of across the air space inside the ring. Only the wires 
on the outer periphery of the ring cut the lines of force; those on 
the inside serving only to complete the electrical circuit. For 
this reason a greater portion of the wire on this armature is 
**dead'' than on a drum armature. 

The disc armature, seldom used in this country, is a drum 



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ELEMENTARY ELECTRICITY 



413 



armature of large diameter and short length, with the greater 
portion of the wire exposed to the pole pieces placed at its ends. 
1835. Field Magnets. In general^ the field magnets of dyna- 
mos are electro-magnets and are bi-polar or multi-polar as they 
possess two or more (an even number of) poles. In the smaller 
machines, which are usually bi-polar, having one north and one 
south pole, the armature is revolved between them; while the 
larger machines, usually multi-polar, have the north and south 
poles arranged in a circle with their faces concentric with the 
armature. The different methods of arranging the coils of both 
bi-polar and multi-polar machines are illustrated in the following 
figures. Figs. 1835a, h, c, d, e. 




Fig. 1835c. 



1836. Windings. The following description of the various 
windings of field magnets is taken in part from Kent and Sheldon. 



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414 ENGINEERING AND SHOP PRACTICE 

Separately Excited. The field magnet coils in this class of 
dynamos have no connection with the armature coils but receive 
their current from a separate machine or source. 

Series Wound (for varying load). In this class of dynamos, 
the field winding and the external circuit are connected in series 
with the armature w^inding so that the entire armature current 
must pass through the field coils. Since, in the series-wound 
dynamo the armature coils, the field and the external circuit 
are in series, any increase in the resistance of the external circuit 
will decrease the electro-motive force from the decrease in the 
magnetizing currents. A decrease in the resistance of the external 
circuit will, in a like manner, increase the electro-motive force 
from the increase in the magnetizing current. The use of a 
regulator avoids these changes in the electro-motive force. 

Shunt Wound (for constant speed). In this class of dynamos 
the field magnet coils are placed in a shunt t^o the armature 
circuit, so that only a portion of the current generated passes 
through the field magnet coil, but all the difference of potential 
of the armature acts at the terminal of the field circuit. In a 
shunt- wound dynamo an increase in the resistance of the external 
circuit increases the electro-motive force; and a decrease in the 
resistance of the external circuit decreases the electro-motive 
force. This is just the reverse of the series- wound dynamo. 

In a shunt- wound dynamo a continuous balancing of current 
occurs, the current dividing at the brushes between the field and 
the external circuit in inverse proportion to the resistance of 
these circuits. If the resistance of the external circuit becomes 
greater, a proportionately greater current passes through the 
field magnets, and so causes the electro-motive force to become 
greater. If, on the contrary, the resistance of the external circuit 
decreases, less current passes through the field and the electro- 
motive force is proportionately decreased. 

Compound Wound. In this class of dynamos the field magnets 
are wound with two separate coils, one of which is in series with 
the armature and the external circuit and the other in shunt 
with the armature. 

Efficiency. The efficiency, at full load, of standard belted 
motors and generators varies from Sl^v in a 1-kilowatt generator, 
87% in a 10-kilowatt, 92% in a 75-kilowatt, to 93% in a 225- 
kilowatt generator. 



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CHAPTER XIX 

POWER TRANSMISSION 
Electric Transmission 

191 1. Efficiency of Electric Systems. The mechanical effi- 
ciency of any system is the ratio existing between the power 
delivered to the generator and the power deHvered by the motor 
at the end of the transmission system. The commercial efficiency 
of a system will vary with the load; however, it is reasonable to 
expect, under favorable conditions, a loss of from 8% to 10% at 
the generator with a like loss at the motor. The loss in trans- 
mission or "drop" is due to the fall in pressure, is governed by 
the size of the wires, and for long-distance transmission varies 
from 4% upward. With the present-day apparatus, the practical 
efficiency of a long-distance transmission system is considered to 
be from 72% to 82%. The longest system known at the present 
writing is that of the Standard Electric Transmission Co., of 
California. The power is transmitted a distance of two hundred 
and fifteen miles and it is stated that the over-all efficiency of 
this transmission measured to the receiving step down trans- 
formers at the terminus was as high, at full load, as 80%. 

There are three general methods of electric transmission: 
(1) The direct-current system. (2) The alternating-current sys- 
tem. (3) The motor-dynamo or regenerating system. 

1912. Governing Conditions in the Selection of Systems. 
The factors or conditions which govern the selection of any 
system are divided by F. R. Hart into those that are fixed and 
those that are variable as follows: the fixed conditions being 
(1) The capacity or source of the power. (2) The cost of power 
at the source. (3) The cost of power by other means at the 
point of delivery. (4) Danger considerations at the motor. (5) 
Operating conditions. (6) Construction difficulties arising from 
length of the line and topography of the country. The variable 
or partially variable factors are: (7) The power and efficiency of 

415 



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416 



ENGINEERING AND SHOP PRACTICE 



the system. (8) The number and size of the delivery units. 
(9) The initial voltage. (10) The pounds of copper on the line. 
(11) Original cost of construction and equipment. (12) Gross 
expenses, operation, depreciation, etc. (13) Liability of trouble 
and stoppage. (14) Danger at station and on line. (15) Con- 
venience in operation, making changes, extension, etc. 

On the assumption that the station equipment will be approx- 
imately a constant, whatever the initial pressure may be, the 
great variation in the cost of wire at different pressures is shown 
by Mr. Hart in the following table (Fig. 1913a) in which he gives 
the weight of copper required for transmitting 100 horse-power 5 
miles. 

1913. Tabulated Transmission Data. 

Weight of Copper Wire Required to Transmit 100 H. P. 5 Miles 



Voltage 


Drop 10% 


Drop 20% 


2,000 

3.000 
10,000 


16,800 Lbs. 
7,400 " 
620 " 


8,400 Lbs. 
3,700 " 
310 " 



Fig. 1913a. 



The subdivisions of each of the general methods of trans- 
mission are tabulated by Kent as follows: 

T ' V U J One Machine. 

1 Machines in Parallel. 



2-Wire. 



Continuous Current.^ 



[One Machine. 
High Voltage. < Machines in Parallel. 
Machines in Series. 



3-Wire. 
Multiple Wire. 



1 2 Machines in Series. 

1 Machines in Multiple Series. 

Machines in Series. 



Alternating Current. 



Alternating Single Phase. 



Alternating Multi-Phase 



I Without Conversions. 
I With Conversions. 

J Without Conversions. 
[With Conversions 



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POWER TRANSMISSION 



417 



Regenerating Sys- 
tems. 



Alternating Continuous. 

Alt<?rnating Converter; Line Converter; Alternating 

Continuous. 
Continuous-Continuous. 
Partial Re-conversion of any system. 

The relative advantages of these systems vary with each 
particular transmission problem, but in a general way may be 
tabulated as follows: 



Syst 



2-Wire^ 



[Lo 



iHii 



3-Wire 



Multiple Wire. 


Single Phase. 


2 


Multiple Phase. 


lg 




Jfc 




£U 




£tj 




Ha: 


Motor-Dynamo. 






^ 




^ 



Low Voltage at Machines 
and Saving in Copper. 



Economy of Copper. 

Economy of Copper, Syn- 
chronous Speed Un- 
necessary, Applicablf 
to very long Distances. 

High Voltage Transmis- 
sion. 

Low Voltage Delivery. 



Copper, 
fficulty of 
f achines. 
Enough in 
r long Dis- 
tances. Necessity for 
"Balanced" System. 



Cannot start under Load. 

Low Efficiency. 
Requires more than 2 

Wires. 



Expensive, Low Effi- 
ciency. 



Fig. 19136. 

Note. Single-phase motors are now made of various patterns 
which can start under full load, such as Wagner, Century, West- 
inghouse Compensated Series Motor, General Electric, etc. It is 
true that such a motor must be larger and more expensive than 
a polyphase; it need not be less efficient except so far as one 
considers weight a factor in determining efficiency. 

1 91 4. Systems of Electrical Distribution in Common Use. 
In a paper before the Engineering Society of Western Penn- 
sylvania, Chas. T. Scott ably discusses the various systems of 
electrical distribution. The following table is abstracted from 
this paper: 

L Continuous or Direct Current. 
A. Constant Potential. 



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418 ENGINEERING AND SHOP PRACTICE 

110 Volts — distances less than, say, 1500 feet. 
For incandescent lamps, 
for arc lamps, usually 2 in series, 
for motors. 
220 Volts — distances less than, say, 3000 feet, 
for incandescent lamps, usually 2 in series. 
For arc lamps, usually 4 in series. 
For motors. 
220 Volts, 3- Wire — distances less than, say, 3000 feet. 
For incandescent lamps. 

For arc lamps, usually 2 in series on each branch. 
For motors; 110 or 220 volts, usually 220 volts. 
500 Volts — distances less than, say, 8000 feet. 
For incandescent lamps; usually 5 in series. 
For arc lamps, iLsually 10 in series. 
For motors, stationary and street car. 
B. Constant Current. 

Usually about 6.6^ amperes, the volts increasing to 
several thousand as demanded. 
For arc lamps. 

* Though formerly used for motors, now seldom 
used on account of power limit and danger from 
excessive voltage. 
2. Alternating Current. 

A. Constant Potential. 

For incandescent lamps. 
For arc lamps. 
For small motors. 
Multi-phase systems. 
For lighting. 
For motors. 
For rotary transformers for giving direct current. 

B. Constant Current. 
Usually 10 amperes. 

For arc lamps. 

1915. Motors, Discussion and Principles. In general, what 

has been said with reference to the principles of the direct -current 

dynamo applies to the motor; in fact, it is the same machine 

with the nature of its operation reversed. In the motor the 

* Rewritten to conform with present practice. 



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POWER TRANSMISSION 419 

electrical energy of the current is transformed into the mechanical 
energy of rotation; in the dynamo only one electro-motive force 
exists, whereas in the motor there must always be two. There 
is no difference between the action of the motor armature and the 
dynamo armature as they revolve in the fields. For the same 
speed and the same current, the same amount of E.M.F. will be 
generated in the motor as In the dynamo; the direction of this 
counter E.M.F., however, tends to send the current in the opposite 
direction. 

The relation and equations are explained as follows by Prof. 
F. B. Crocker: 

1 kilowatt dynamo I = E -^ R; 10 amperes = 100 volts -^ 10 ohms. 

, , ., ,, , J E-e .^ 100 volts - 90 volts 

1 kilowatt motor / = — - — ; 10 amperes = :; — r . 

Ri ' ^ 1 ohm 

/ is the current; E the direct E.M.F. ; e the counter E.M.F. ; R, 
the total resistance of the circuit; and R^ the resistance of the 
armature. The current and direct E.M.F. are the same in the 
two cases, but the resistance is only tV as much in the case of 
the motor, the difference being replaced by the counter E.M.F., 
which acts like resistance to reduce the current. In the case of 
the motor, the counter E.M.F. represents the amount of the 
electrical energy converted into mechanical energy. The so-called 
electrical efficiency or conversion factor = counter E.M.F. -^ direct 
E.M.F. The actual or commercial efficiency is somewhat less 
than this owing to friction, Foucault currents, hysteresis, etc. 

The work of a motor depends on the product of two factors, 
torque and speed. The torque, which is the twisting moment or 
effort of the armature, is measured in foot-pounds and is found 
by multiplying the radius of the armature pulley in feet by the 
pounds pull on the belt. Torque may be measured directly as 
the force in pounds at one foot radius, i.e., the pull on a belt 
running on a pulley 2 feet in diameter. 

In general, the conditions under which motors operate may 
be divided as follows: (1) Those operating at a constant-speed 
and variable torque; best adapted for this purpose are the ordi- 
nary direct-current shunt-wound motors which operate on con- 
stant-potential circuits — the work of driving a line shaft being 
typical, for a constant speed must be maintained regardless of 
the number of machines in operation. (2) Those which operate 



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420 ENGINEERING AND SHOP PRACTICE 

at a variable speed with a constant torque; best adapted for 
these conditions are the series-wound motors operating on con- 
stant-potential circuits, their typical service being the driving 
of cranes, hoists and elevators where a constant load is operated 
at a variable speed. (3) Those which operate at a variable speed 
with a variable torque; best adapted for these conditions is the 
series-wound motor operating on a constant-potential circuit — 
the typical conditions being found in the operation of street 
railway motors, where in starting the torque is at maximum 
while the speed is at minimum, and where, as the car gains head- 
way, the torque diminishes as the speed increases. Many series 
motors for trolley cars are so wound as to have a saturated field 
at practically all speeds, so that variations of current do not 
cause variations of speed. If field varies as current, then torque 
varies as square of current, which causes too rapid a falling off 
in torque as speed increases. 

On the direct-current circuits, the characteristic action of 
the series- wound motor is to build up the field and the output as 
the load increases; whereas in the shunt- wound motor the field 
strength falls as the load increases — the compound winding 
being much used to operate textile machinery where any slight 
variation in the speed would affect the character of the product. 
The reader is referred to Chapter XX, on Motor Drives, etc., where 
much recent additional information may be found regarding 
motors, their application and regulation. 

1916. Motor Speed Regulation. The accepted methods of regu- 
lating motor speed are, by inserting resistance in the armature of 
shunt- wound motors; by varying the field strength of series- wound 
motors; and by switching sections of the field coils in or out of 
circuit. Field regulation is now an accepted practice with shunt- 
wound motors for controlling speed. As great a variation as 6 to 
1 can be thus obtained, giving full power at all speeds. Addi- 
tional information regarding motor speed regulation may be found 
in Chapter XX — Motor Drives and Motor Driven Machine Tools. 

1917. Alternating-current Motors. The majority of the 
alternating-current motors in common use may be divided into 
two classes, viz., synchronous and induction motors. If any 
alternator be brought into synchronism with the alternator 
generating the current, it may be used as a motor, the action of 
the two being similiar to the action of two generators in parallel. 



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POWER TRANSMISSION 421 

1918. Sjmchronous Motors. Synchronous motors are almost 
identical in construction with the driving alternator, operate on 
single or polyphase systems, and consist of two essential parts, 
the field and the armature, either of which may revolve. The 
field of synchronous motors must be excited in the same way as 
the alternator, by a separate, continuous current. The drawback 
to those operating on a single phase being that they are not 
self-starting but must be brought into synchronism with the 
alternator by some external means. 

Polyphase motors, however, are self-starting, that is, with no 
load. It is better to bring them to speed by independent means 
on account of the large current necessary to start them. Such 
machines are usually started by a small induction motor; or in 
such as have the field excited by a small direct-current gener- 
ator belted to the motor, by operating this generator as a motor 
to start. 

The effect of weakening the field of a direct-current motor is 
to increase the speed, while the current flowing through the 
armature remains practically unchanged. No such change of 
speed occurs if the field strength of a synchronous motor be 
changed, for such a motor has to keep step with the alternator. 
The adjustment to the changes of load and field strength being 
effected in such a motor by changing the phase difference between 
the current and the E.M.F. As the load varies, the current in 
the motor either leads or lags behind the E.M.F. and the E.M.F. 
will no longer be in opposition to that of the alternator, resulting 
in a constant flow of current sufficiently large to enable the motor 
to carry its load. When the machine is too much overloaded, 
this lagging of one armature behind the other becomes suflSciently 
great to throw the motor out of synchronism, that is, to fall out 
of phase with the generator and cause it to stop. 

For economy in operation, synchronous and induction motors 
are sometimes placed in the same circuit. In such an arrangement 
the synchronous motor may be made, by increasing the field 
excitation, to cause the current to lead, while the induction motor 
causes it to lag; this balancing effect being conducive of efficiency. 
Synchronous motors are best adapted for power transmission 
plants and for large power units of high voltage, with a constant 
load and speed. The drawbacks to this class of motors are the 
necessity of excitation and the inability to start. 



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422 ENGINEERING AND SHOP PRACTICE 

1919. Induction Motors. Induction motors are sometimes 
made to operate on single-phase circuits, but they are more gen- 
erally operated on two- or three-phase circuits. The two essential 
parts of an induction motor, either of which may revolve, are the 
primary or field which is connected with the line, and the secon- 
dary or armature in which are induced the currents by the pri- 
mary. ' 

Comparing the action of the two motors, we have the current 
led into the armature from the line in a synchronous or in a 
direct-current motor, the reaction of these currents upon the 
fixed field producing the motion; while with the induction motor 
the current is led from the line into the field to produce a mag- 
netic field which constantly changes or rotates and which induces 




Fig. 1919. — Rotating Field. 

currents in the armature coils. The reaction of these induced 
currents on the field results in motion — in most cases of the 
armature — hence the name induction motors. 

The rotating field being distinctive of the induction motor, 
we wall consider its action on a two-phase circuit with a four-pole 
field: 

The poles 1 and 2 (Fig. 1919) are w^ound from one of the pairs 
of wires while 3 and 4 are wound free from the other; the two- 
phase being 90° apart. At the instant that 1 and 2 are receiving 
a maximum current, 3 and 4 are demagnetized. As the cycle pro- 
gresses, the magnetism of 1 and 2 decreases while that of 3 and 4 
increases, resulting in a shifting or rotation of the field area of 
maximum intensity. It must be understood that the rotating re- 
fers to this shifting of the field rather than to any motion or revo- 
lution of the primary. The armature wuthin this field rotates 
simply by the shifting effect without the use of collector rings; the 



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POWER TRANSMISSION 423 

revolving part is termed the rotor and the stationary part of the 
motor the stator, and in order that such a motor may carry a load 
some slip is necessary so that the conductors in the rotor may 
cut lines of force and induce currents. The greatest torque is 
exercised when such a motor is standing still and is directly, as 
is the output, proportional to the square of the pressure in the 
primary; the minimum torque being when running in synchronism 
with the rotating field. 

The induction motor, it will be seen, possesses most of the 
advantages of the direct-current motor, in that it has a large 
starting torque and may be started and stopped frequently; also, 
when overloaded the induction motor will slow down until the 
induced currents in the armature are sufficient to carry the load. 

Compressed Air Transmission 

1921, Compressed Air. The following discussion of the ther- 
modynamics of air compression is taken in part from a treatise 
on the physical properties of gases by Kimball. 

All the work which is required to compress air is converted 
into heat, as is evidenced by the rise in temperature of the com- 
pressed gas. In practice, many devices are employed to carry 
off the heat as fast as it is developed, in order that the temperature 
may be kept down. It is not possible, however, in any way to 
totally remove this difficulty. The question may arise whether, 
if all the work done in compression is converted into heat and 
this heat gotten rid of as rapidly as possible, the work is not vir- 
tually thrown away and the compressed air possesses really no 
more energy than it had before compression. If the temperature 
is no higher, it is true that the compressed gas has no more energy 
than is had before compression, but the advantage of compression 
lies in bringing its energy into a more available form. The total 
energy of the compressed air and uncompressed gas is the same 
at the same temperature; however, the available energy is much 
greater in the former. Whenever compressed air performs work 
in driving machinery, it gives up energy equal in amount to the 
work performed and its temperature is thereby greatly reduced. 
Zahner, in his work on *' Transmission of Power by Compressed 
Air," concludes that, since the compression of air always develops 
heat and that, as this compressed air is always allowed to cool 
down to the temperature of the surrounding atmosphere before 



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424 ENGINEERING AND SHOP PRACTICE 

it is used, the mechanical equivalent of this dissipated heat is 
lost. This loss is unavoidable. 

As the heat of compression increases the volume of the air, it 
is necessary to carry it to a higher pressure in the compressor in 
order that we may finally have a given volume of air at a given 
pressure and at the temperature of the surrounding atmosphere. 
The work expended in securing this excess of pressure is also lost. 

Another source of loss of energy in a compressed-air system 
is the friction of the air in the pipes, leakage, dead spaces, the 
resistance offered by insufficient valve area and the valves, 
inferior workmanship and slovenly attendance. 

In the adiabatic compression of air, all the heat resulting from 
the compression is retained in the compressed air, while in the 
isothermal compression of air the heat is removed as rapidly as 
produced by means of some form of refrigerator. 

That energy which a fluid or gas is capable of exerting against 
a piston in changing from a given volume and temperature to a 
total privation of heat and indefinite expansion is termed its 
intrinsic energy. 

1922. Air Compressors. A detailed description of any one 
of the hundreds of different air compressors on the market is 
deemed unnecessary; it being sufficient to state that in principle 
the simple air compressor is an air pump consisting of a cylinder 
with suitable inlet and outlet valves in which a piston operates, 
first to draw into the cylinder through the inlet valve a certain 
quantity of air, and next to compress this air to a certain pressure 
and to force it through the outlet valves into the receiver, which 
latter is usually a tank. 

1923. Compressed-air Engines and Machines. The com- 
pressed-air engines on the market, as well as other compressed- 
air machinery, vary widely in detail and design, according to the 
work to be performed and the ideas of the manufacturer. It 
may be stated, however, that most of the air engines and tools, 
like steam engines, have reciprocating pistons, valves and parts, 
and the air is used in much the same way that steam is used in 
steam engines. Compressed air is used extensively in mining 
operations, not only for driving hoisting engines, rock drills and 
underground pumps, but for operating the locomotives as well. 
Where compressed air is used to drive machines in mines and 
tunnels, the loss of power in common practice is about 70%; the 



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POWER TRANSMISSION 425 

best practice having a loss of about 60%. In the machine shop, 
compressed air is being widely used for operating pneumatic 
hammers, drills and riveters; for air hoists and light cranes and 
for cleaning castings and machines. Compressed air is used to 
furnish the blast for various furnaces, cupolas, etc. When so 
used the pressures are comparatively low and some form of 
blower is generally employed, the pressure varying from a few 
ounces to three quarters of a pound. Compressed air is also 
used for pneumatic tube service in which small carriers are forced 
through smooth tubes. 

Hydraulic Transmission 

193 1. Adaptability and Uses. When the moving of very 
heavy loads at low velocities is to be effected, water under a 
pressure generally of from 700 to 2000 pounds per square inch 
affords an efficient method of transmitting power to a distance, 
the application being the operation of elevators, cranes, presses, 
Ufting-jacks and similar machinery. The system usually consists 
of one or more pumps capable of developing the required pressure; 
accumulators, which are vertical cylinders with heavily weighted 
plungers passing through stuffing boxes in the other end, by 
means of which a quantity of water is accumulated at the pres- 
sure to which the plunger is weighted; the distributing pipes and 
the machinery to be operated. 

1932. Hydraulic Forging. One of the important uses of 
hydraulic power transmission is in the operation of heavy forging 
machines for the compression of steel ingots while in a fluid state; 
the operation of hammers, flanging, and forging presses and 
riveting machines. For the production of massive steel forging, 
the hydraulic forging press has superseded the steam hammer. 
When a steam hammer was employed for this purpose, it was 
noted that the external surface of the ingot absorbed a large 
proportion of the sudden impact of the blow and that only a 
comparatively small effect was produced at the central portions 
of the ingot, this being due to the resistance offered by the inertia 
of the mass to the rapid motion of the falling hammer. This 
disadvantage is entirely eliminated by the slow, though powerful, 
compression effected by the hydraulic forging press. 

Some idea of the size of hydraulic forging presses and also 
the extent to which they are used may be gained from the state- 



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426 ENGINEERING AND SHOP PRACTICE 

ment that a forging press has been designed by John Fritz for 
the Bethlehem Works, of 14,000 tons capacity, to be run by 
engines and pumps of 15,000 horse-power. The plant is served 
by 4 open-hearth steel furnaces of a united capacity of 120 tons 
of steel per heat. 

The efficiency of a hydraulic apparatus of direct plunger or 
ram type varies from 92% to 94%. 

Rope Transmission 

1941. Wire Rope Transmission. Where large powers are to 
be transmitted over rough ground or waterways to a distance 
not exceeding two or three miles, wire-rope transmission is some- 
times best adapted to the conditions which obtain. The rope, 
generally made of fine steel wire, is usually composed of 7, 12 or 
19 wires and operates in the transmission in the same way that a 
belt does. The sheaves (rope wheels) are usually made strong, 
as light as possible and of cast iron. The bottom of the groove 
in which the rope runs is filled with various substances, such as 
jute yarn, tarred oakum, hard wood, leather and rubber; a very 
satisfactory filling being composed of segments of leather and 
blocks of India rubber, soaked in tar, packed alternately in the 
groove. The maximum distance between sheave towers, the 
sheaves being 10 feet in diameter, is given by Kent as 600 feet, 
though an exceptional drive at Lockport, N. Y., has a clear span 
of 1700 feet. 

It is customary to transmit the power with the lower portion 
of the rope, as the greatest deflection usually occurs in this portion 
when idle. Practice demonstrates that the life of a rope is 
longest when the bending over sheaves is all in one direction, and 
when the sheave diameter is large, that is, over 100 rope diam- 
eters for steel and 180 for iron wire. 

In some transmissions, instead of grooved drums or a number 
of sheaves about which the rope makes two or more laps, grip 
pulleys are sometimes used. The rims of such pulleys are fitted 
with a continuous series of steel jaws which bite the rope in 
contact by reason of the pressure against them, releasing it as 
soon as the pressure is relieved and offering free egress to the 
rope. 

1942. Rope Driving. In mills and factories where the power 
is large and the distance it is to be transmitted comparatively 



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POWER TRANSMISSION 



427 



great, rope drives compare favorably with the shafting, belting 
and gearing system and for a certain class of work are rapidly 
superseding them, owing to the formcr^s higher efficiency and 
greater flexibility. The advantages and applications of such a 
system become apparent when we consider that a perfect align- 
ment of sheaves is unnecessary, that the shafts may be placed 
at any angle with each other and at any reasonable distancQ apart ; 
in fact, it would be difficult to conceive of a combination of 
shafting and pulleys as to angles and position that would not 
lend itself readily to a rope drive. 

1943. Systems. In practice, there are two systems of rope 
drives, namely, the multiple and the continuous systems. In the 




Main Drive for'Coilon Mill 
lic»i):ncd b> C R Malcrprair \ Cp 



Fia. 1943a. — Multiple System Drive. 



multiple system a number of single, independent rope belts run 
side by side, each being spliced on the pulleys very taut and 
running until the stretching is sufficient to make them slip when 
they are re-spliced. In the continuous system, a single rope is 
wound around the grooved pulleys several turns, enough times 
to transmit the required power; and a tension pulley, to give the 
necessary adhesion, is placed where it will take care of the slack 
at the point at which it naturally accumulates. Generally, the 



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428 ENGINEERING AND SHOP PRACTICE 



Fig. 19436. — Continuous System, Horizontal Drive. 



Fig. 1943c. — Continous System, Vertical Drive. Tension taken at Driven. 



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POWER TRANSMISSION 429 

last strand from the driver leads over an idler sheave, mounted 
at the side of or near the driven pulley, to the tension pulley, from 
which it is returned to the groove on the opposite side of the 
driven pulley. 

ig44. Sheaves and Pulleys. A sheave wheel or pulley is one 
made of cast iron, in the rim of which are formed deep grooves 
of suitable shape to receive the turns of the rope. If several 
grooves are cut in one pulley, they must all be of the same shape. 



Fia. 1944a. — Standard Drive Groove. 



Fig. 19446. — Straight-side Drive Groove. 



Fig. 1944c. — Idler Groove. 



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ENGINEERING AND SHOP PRACTICE 



size and diameter at the pitch line, in order to prevent creeping 
or slippage, cither of which results in an undue straining of certain 
portions of the drive. The contour of a groove of accepted form 
is shown in Fig. 1944a, the sides being curved. The " Engineer's 
Standard Grooves," designed by the Jones & Laughlin Steel Co., 
are nine in number, and though similar to the shape shown in 
Fig. 1944a, are not in accordance with the proportions given. 
Fig. 19446 is a form sometimes used but is not as good as that 
shown in 1944a. Tangents to the side at the pitch line are at 
an angle of 45°. The sides are so shaped that the rope in wedg- 
ing on them results in the production of a high frictional resist- 
ance to slipping. The concave sides cause a rolling motion in 
the rope, which is beneficial in its production of a uniform wear. 
In practice, the surfaces of the grooves should be carefully pol- 
ished, as any roughness, due to the tool-marks or imperfections in 
the casting, rapidly cuts the rope. 

The shape of the groove in the idler pulley, as will be seen in Fig. 
1 944c, is semicircular at the bottom with a radius slightly larger 
than the radius of the rope. In the following table (Fig. 1944<f), 
taken for the most part from American Mfg. Go's " Blue Book," will 
be found some useful data relative to both pulleys and ropes. 

Data Relative to Manila Transmission Rope and Sheaves 



o> a 
1.2 



B 
S 

c5? 



«-9 

»o q 

< 



i 
i 
1 

n 

H 

n 

2 

2i 
2i 



.25 


.12 


.3906 


.16 


.5625 


.20 


.7656 


.26 


1. 


.34 


1.2656 


.43 


1.5625 


.53 


2.25 


.77 


3.0625 


1.04 


4. 


1.36 


5.0625 


1.73 


6.25 


2.13 



1750 

2730 

3950 

5400 

7000 

8900 

10,900 

15,700 

21,400 

28,000 

35,400 

43,700 



li 
.11 



50 

80 

112 

153 

200 

253 

312 

450 

612 

800 

1012 

1250 



Length of Splice in Feet 



6 
6 
6 
6 

7 
7 
7 
8 
8 
9 
9 
10 



8 
8 
10 
10 
10 
12 
12 
14 
14 
16 



14 
16 
16 
18 
18 
20 
20 
22 



ll 



C/J 



20 
24 
27 
32 
36 
40 
45. 
54 
63 
72 
81 
90 



H 
I 



1060 
970 
760 
650 
570 
510 
460 
380 
330 
290 
255 
230 



Fig. 1944rf. 



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431 



With a given velocity of the driving rope, the weight of rope 
required for transmitting a given horse-power is the same, no 
matter what size rope is adopted. The smaller rope will require 
more parts but the weight will be the same. 

1945. Transmission Rope. The material most suited for 
transmission rope is the best grade of cotton and manila. Trans- 



95 




55 



Fia. 1945a. — Horse-power of Manila Ropes at Various Speeds. 

mission rope of manila is generally made of 3, 4 and 6 strands; 
the 4 and 6 strand ropes having a central core around which the 
other strands are laid. 

Cotton rope is used largely for service which operates on 



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ENGINEERING AND SHOP PRACTICE 



5© 


Velocity, Feet per Minute 


1,000 


IJXO 


S.00O 


S^iOO 


d,ooo 


8,500 


4,000 


4^ 


6,000 


6,500 


6,000 


H 


3.3 


8.8 


4.3 


5.2 


6.0 


6.6 


7.2 


7.3 


7.4 


7.8 


6.9 


n 


8 


45 


5.9 


7.0 


8.2 


9.0 


9.6 


9.8 


10.0 


9.6 


9.0 


1 


4.0 


5.9 


7,7 


9.2 


10.6 


11.8 


12.7 


12.9 


18.0 


12.7 


12.0 


VA 


^,0 


7.5 


9.7 


11.6 


13.5 


149 


16.0 


16.8 


16.7 


16.5 


15.8 


VA 


6.8 


9.1 


12.0 


14.3 


16.7 


18.5 


20.0 


20.2 


20.7 


20.1 


18.9 


IH 


9.0 


13.6 


17.4 


20.7 


23.0 


26.3 


2a7 


29.0 


29.5 


28.6 


26.7 


1^ 


12.3 


18.0 
23.2 


28.6 


28.2 


32.7 


36.4 


88.5 


89.4 


40.5 


38.7 


36.0 


2 


16.0 


80.6 


36.8 


42.5 


46.7 


50.0 


51.7 


52.8 


50.6 


47.3 


2^ 


20.0 


29.6 


38.6 


46.6 


53.6 


59.2 


63.6 


65.8 


66.3 


64.4 


60.3 


3M 


250 


86.6 


47.7 


57.5 


66.0 


71.2 


78.0 


80.0 


81.0 


79.0 


73.8 



Fig. 19456. — Horse-power of Manila Ropes at Various Speeds. 

sheaves of small diameter; it is more expensive, less durable, has 
less strength and is harder to splice than the manila rope. 

The wear on transmission rope is both external and internal. 
The external is caused by the slipping and wedging in the grooves 
of the pulley; while the internal is caused by the movement of 
the fibers on each other under pressure in bending over the 
sheaves. In ordinary practice the wear is assumed to be directly 
proportional to the speed. Transmission rope manufacturers 
seek to lessen internal wear by the free use of such lubricants as 
graphite and tallow on the core and inner strands of the rope. 

The foregoing diagram (Fig. 1945a) and table (Fig. 19456) give 
the horse-power of manila ropes at various speeds and are calcu- 
lated on the basis of a maximum strain of two hundred pounds 
for a rope one inch in diameter. It will be readily seen that the 
maximum power, under these conditions, is transmitted at a speed 
of about 80 feet per second; at higher speeds, the power falls off 
rapidly because of the excessive centrifugal force. 

1946. Splicing. The splicing of a transmission rope is an 
important matter; the points on which the success of the splice, 
and incidentally the drive, depend being the length of the splice, 
which in turn depends upon the diameter of the rope and which 
is given in the table (Fig. 1944d) ; the diameter of the splice, 
which should be the same as the diameter of the rope; the secur- 
ing of the ends of the strands of the splice, which must be so 
fastened that they will not wear or whip out or cause the over- 
lying strands to wear unduly; and the workmanship of the splice, 



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POWER TRANSMISSION 433 

which should be the best it is possible to secure. When splic- 
ing an old and a new piece of rope, the new piece should be 
thoroughly stretched for, at best, it is an exceedingly difficult task 
on account of the stretch and difference in diameter of the rope. 

The illustrations and instructions for making standard rope 
splices are taken, by the courtesy of the American Manufacturing 
Co., from their **Blue Book of Rope Transmission." 

There are many different splices now in use, but the one that ex- 
perience has proved best is what is known as the English transmis- 
sion splice. In describing this we take for our example a four-strand 
rope, li" in diameter, as spliced on sheaves in the multiple sys- 



FiG. 1946a. 

tem. The rope is first placed around sheaves, and, with a tackle, 
stretched and hauled taut; the ends should pass each other from 
six to seven feet, the passing point being marked with twine on each 
rope. The rope is then slipped from the sheaves and allowed to 
rest on shafts, to give sufficient slack for making the splice. 

Unlay the strands in pairs as far back as the twines ilf , A/', 
crotch the four pairs of strands thus opened (Fig. 1946a), cores 
having been drawn out together on the upper side. Then, having 
removed marking twine Af, unlay the two strands 6 and 8, still 
in pairs, back a distance of two feet, to A; the strands 1 and 3, 
also in pairs, being carefully laid in their place. Next unlay the 
strands 5 and 7 in pairs, to A'y replacing them as before with 
2 and 4. The rope is now as shown in Fig. 19466. The pair of 
strands 6 and 8 are now separated, and 8 unlaid four feet back 



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ENGINEERING AND SHOP PRACTICE 



to Bj a distance of six feet from center, strand 6 being left at A. 
The pair of strands 1 and 3 having been separated, 3 is left at A, 
as companion for 6, strand 1 being carefully laid in place of 
strand 8 until they meet at point B, The two pairs of strands 
2-4 and 5-7 are now separated and laid in the same manner, 
every care being taken, while thus putting the rope together, 
that original twist and lay of strand is maintained. The pro- 
truding cores are now cut off so that the ends, when pushed 
back in rope, butt together. 



Fig. 19466. 



The rope now appears as shown in Fig. 1946c, and after the 
eight strands have been cut to convenient working lengths (about 
two feet), the companion strands are ready to be fastened together 




Fig. 1946c. 



and 'ducked"; this operation is described for strands 2 and 7, 
the method being identical for the other three pairs. Unlay 
2 and 7 for about twelve to fourteen inches, divide each strand 



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POWER TRANSMISSION 435 

in half by removing its cover yarns (see Fig. 1946d), whip with 
twine the ends of interior yarns 2' and 7'; then, leaving cover 2, 
relay 2' until near 7 and 7', here join wuth simple knot 2' and 7', 
Fig. 1946e. Divide cover yarns 7, and pass 2' through them, 
continuing on through the rope under the two adjacent strands, 
avoiding the core, thus locking 2', Fig. 1946/. In no event pass 2' 



Fig. 1946d. 



over these or any other strands. Half-strand 7' must now be taken 
care of; at the right of the knot made with 2' and 7', 2' is slightly 
raised with a marlin spike, and 7' passed or tucked around it 
two or three times, these two half-strands forming in this way a 



Fig. 1946e. 

whole strand. Half-strand 7' is tucked until cover 2 is reached, 
whose yams are divided and 7' passed through them and drawn 
under the two adjacent strands, forming again the lock. The 
strand ends at both locks are now cut off, leaving about two 



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436 ENGINEERING AND SHOP PRACTICE 

inches, so that the yarns may draw slightly without unlocking. 
This completes the joining of one pair of strands, Fig. 1946^. 
The three remaining pairs of strands are joined in the same 
manner. 



Fig. 1946/. 

After the rope has been in service a few days, the projecting 
ends at locks wear away, and if tucks have been carefully made, 
and the original twist of yarns preserved, the diameter of the 



Fig. 1946^. 

rope will not be increased, nor can the splice be located when the 
rope is in motion. 

Shaft, Pulley and Belt Transmission 

1951. Shafting. With the exception of engine and special 
shafting, almost all of the shafting in use to-day is manufactured 
from mild steel, it being finished round, true and smooth, either 
by cold rolling, turning or grinding. The final sizing of turned 
shafting is made by passing a hollow tool over it. As the shafting 



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POWER TRANSMISSION 437 

is usually made from commercial stock, the sizes run ^^ under 
that of the bar, that is m% m" and 2^*. 

In calculating the strength of shafts, two things must be 
considered, the resistance to torsion or twisting and the resistance 
to bending. With reference to the kind of stress to which they 
are subjected, shafts may be classified, according to the predomi- 
nating stress, into those subject chiefly to torsion or twisting 
stresses, such as shafting in general and line shafting in mills 
and shops; those subject to bending action such as studs or 
axles of gears; and those which are subject both to stresses of 
torsion and bending, such as the crank shafts of engines. 

Shafting may be divided, according to use, into three kinds: 
jack shafting, line shafting and counter shafting. The jack shaft 
is belted directly from the engine, while the line shaft is belted 
from the jack shaft, the term being applied to the long lines of 
shafting used for transmitting the power through the shops; the 
term countershaft is applied to that shaft which receives its power 
from the line shaft and transmits it through tight and loose pul- 
leys or clutches to the machine. In addition to the torsional 
stress due to power transmission, line shafting is also subject to 
bending stresses which are due, not only to the weight of the 
pulleys and couplings, but also to the tension of the belting as 
well. 

As previously stated, in any computation for the strength of 
shafting, both the resistance to torsion and the bending must be 
considered. If we wish to determine the diameter of a particular 
shaft, we find, in our various authorities, some such formulas as 
these: 



(1) Z) = C'y/^ and (2) D^C\^l 



(HP 
N 
The above formulas have their origin in the simpler ones of 

(3) Z) = CV^FL and W D^C.^yfL 



where D equals shaft diameter, C equals constant for the material, 
F equals force tending to rotate the shaft and L equals length in 
inches from the point of application of F to the center of the shaft. 
Formula 3 is based on the fact that, under this condition, the 
torsional deflection of the shaft shall not exceed a predetermined 
angle per foot in length; and formula 4, under the condition that 



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ENGINEERING AND SHOP PRACTICE 



the moment FL produces a torsional stress, not more than a 
predetermined amount per square inch. In formulas 1 and 2 
HP equals horse-power transmitted by the shaft, and N equals 
the number of revolutions per minute. 

When shafts are subject to combined bending and torsional 
stresses, a value M should be used in formul as 3 and 4, where M 
is determined from the equation, M = B\/B^ + T^, M being the 
ideal twisting moment, which would have the same effect as B 
and T acting together; B equals the bending and T equals the 
twisting moment. 

The following table gives the values for C, C\, C and C^ under 
a limited range of varying conditions. Formula 1 may be used 
for all solid shafts under 11 inches in diameter, while formula 2 
may be used for shafts of larger size. 



Material 


C'for 
Round Shafts 


C'for 
Round Shafts 


Cfor 
Round Shafts 


Cifor 
Round Shafts 


Steel 


4.7 

4.92 

5.59 


3.3 

3.62 

4.56 


.297 

.31 

.353 


.0828 


Wrought Iron . . . 
Cast Iron 


. .0909 
.1145 



Fig. 1951. 

In general practice line shafting in shop and factory is seldom 
under I}'' in diameter, its speed, of course, being determined by 
the speed of the driving belt and pulleys; however, 125 to 175 
revolutions per minute was the general speed for machine shops 
before the advent of high speed cutting tools; now double these 
values are often used; while, for shafts driving wood- working 
machinery, the speed is from 200 to 250 revolutions per minute. 

1952. Shafting Supports. The distance between bearings is 
generally about 8 feet so that the couplings, when 16-foot shafting 
is used, may come close to the bearing. The distance between 
the bearings, however, is dependent upon the weight and the 
power transmitted and for shafts heavily loaded with pulleys, or 
transmitting large power, the bearings should be closer together. 

The following table (Fig. 1952), giving maximum distances 
between bearings, for the various shaft diameters, is computed on 
the assumption that a deflection of more than jj^r*' P^r foot of 
length is inadmissible. 



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POWER TRANSMISSION 439 



Stbxl Shafting 



Shaft Diameter in Inches 


Maximum Distance between Bearings in Feel 


2 


11.5 


3 


13.75 


4 


15.75 


5 


18.25 


6 


20 


7 


22.25 


8 


24 


9 


26 



Fio. 1952. 

1953. Bearings and Hangers. Bearings is the term applied 
to the pieces of mechanism in which the shaft is carried and 
rotates. They are sometimes called boxes. When the shaft is 
suspended from the ceiling, the bearing is usually suspended in 
a cast-iron frame called a hanger; the same frame when set on 
the floor becomes a floor stand, and when fastened to the wall or 
to a post it is termed a post-hanger. Hangers are usually pro- 
vided with some method of securing alignment of their bearings 
with the bearings in other hangers. The most important part, 
however, of the hanger is the bearing, which should be lined with 
a good quality of bearing metal and provided with some form of 
self-oiling device. A self-oiling bearing usually contains a reser- 
voir from which the oil is carried to the shaft by means of a ring 
or chain running on the shaft, or by suitable wicks in contact 
with the shaft. 

1954. Pulleys, Clutches and Couplings. Commercial pulleys 
are manufactured either of cast iron, steel or wood and may be 
either split, solid, tight or loose. Split pulleys are made in 
halves and may be placed on the shaft at any point, while the 
others must be put on from the ends. 

The face or periphery of all pulleys is trued and polished 
while the lx)re is machined and reamed to fit the shaft to which 
the pulley is fastened by means of set screws or keys. 

Cast-iron pulleys should always be balanced and those of 
extra wide face should be provided with two sets of arms. 

Steel pulleys sometimes consist of a steel rim which is riveted 
to a cast-iron or steel center or spider, while small ones are made 



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ENGINEERING AND SHOP PRACTICE 





S 



r 



•3 
I 

£ 



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POWER TRANSMISSION 441 

entirely of one piece of pressed steel; the advantage effected by 
such an arrangement being a strong, light pulley free from internal 
strains. 

Wood pulleys are almost always made in halves and are built 
up of small sections of hard wood, well glued and doweled to- 
gether. They are provided with bushings to fit any sized shaft, 



Fig. 19546. — Dodge Compression Clutch. 

to which they are secured by a clamp hub. Wood pulleys are 
seldom used in machine shops; however, owing to their lighntess 
they are well adapted to high-speed work. 

Loose pulleys turn freely on the shaft, are used to carry a 
shifting belt and are made flat or straight-faced, while tight 
pulleys are crowned — that is, are of larger diameter at the middle 
of the face. 



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ENGINEERING AND SHOP PRACTICE 



Clutches. A clutch-pulley is often used where it is necessary 
to start or stop a tight pulley frequently, such as the tight pulley 
of a countershaft. In the clutch shown in the illustration, Fig. 
1954a, the clutch is keyed to the shaft while the pulley runs 
free; when the sleeve is slipped toward the hub of the clutch, 
the toggle-joint closes the jaws which grip the pulley rim firmly, 
causing the whole to revolve with the shaft. Clutch and loose 
pulleys should always be provided with long bushings and suitable 
devices for automatic lubrication. 

Couplings. The device for fastening two pieces of shafting 
together is termed a coupling. There are several kinds of coup- 




FiQ. 1954c. — Solid Sleeve Coupling. 



Coupling. 



lings on the market, the more common kinds being the flange, 
the compression, dental or jaw and universal couplings. Flange 
face-couplings are fitted to the ends of the shaft and the faces 
turned in place to insure accuracy and alignment. There are 



Fig. 1945c. — Ribbed Compression Coupling. 



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POWER TRANSMISSION 



443 



many designs of compression couplings, each possessing more or 
less intrinsic merit. A simple kind consists of two semi circular 
shells — one of which carries a key-way — which are bolted 
together over the shaft, the shaft joint being made at the middle. 





Fig. 1954/. — Straight and Spiral Jaw Couplings. 



The key provides a positive drive, while to insure against move- 
ment a pin is inserted in the clutch and shaft at each end. 

The jaw clutch is used where it is convenient to disconnect 
one piece of shafting from the other; this uncoupling being effected 
by merely sliding one side of the coupling along on the shaft. 




Fio. 1954y. — Universal Joint Coupling. 

A glance at Fig. 1954^ reveals the construction and details of 
the universal coupling; the forks in heavy machinery being forged 
and welded to the shaft. This coupling is seldom satisfactory 
when operated at angles exceeding 15^. However, some designs 



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444 ENGINEERING AND SHOP PRACTICE 

will act under certain conditions at an angle of 25° or greater. 
The objection to the universal joint is the fact that it does not 
transmit a uniform motion; the velocity of the driven shaft 
varying twice during one revolution between a velocity that is 
greater and one that is less than the driver. 

1955. Arrangement of Shafting and Pulleys. When a hori- 
zontal open belt runs over but two pulleys, the driving should 
be done with the lower side of the belt, for the reason that the 
arc of contact is much greater in this case. 



Fig. 1955a. — Pulley Crowning. 

Idler pulleys work most satisfactorily when located on the 
slack side of the belt about one quarter away from the driving 
pulley. It is almost impossible to operate a vertical belt satis- 
factorily without an idler pulley, consequently the belts from 
counterahafting should incline somewhat toward the machine. 
Idler or tightener pulleys operate most satisfactorily when of 
liberal diameter; noise, wear and injury to the bilt due to short 
reverse bands are thus obviated. 

It is common practice to have one belt run on top of the other 
on the driving pulley when two parallel shafts are driven from it. 



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POWER TRANSMISSION 



445 



Driving pulleys are crowned because the belt tends to run on 
the larger diameter of the pulley. 

In the Fig. 19556, if for any reason the belt is forced to one 




Fig. 19556. Fig. 1955c. 




Fio. 1955d. — Quarter Twist Belt. 

side, that edge nearest the center of the pulley is stretched and 
travels faster than the outer edge. This causes the belt to center 
itself on the pulley. A belt only runs to the high side of a pulley 



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446 



ENGINEERING AND SHOP PRACTICE 



when the shafts are parallel; if the shafts are not parallel, the 
high side of the pulley is due to its position rather than to its 




Fig. 1955c. — Quarter Twist Belt with Two Tighteners. 

shape, and the belt runs to the low side for the reason that it 
passes on to the pulley in a spiral direction. All points as they 





FiQ. 1955/. — Mule Pulleys for Angle Belts. 

first come in contact with the pulley being carried in the direction 
of the pulley's rotation as indicated in Fig. 1955c. 

Quarter tw^st belts are used for connecting shafts at right 



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POWER TRANSMISSION 447 

angles with each other in different planes. Three things are 
necessary for a successful quarter twist drive. The pulleys must 
be so placed that the belt leads from the center of the face of one 
to the center of the face of the other; the shaft centers must be 
reasonably far apart and the pulleys have a face somewhat wider 
than those used when driving straight. The direction of rotation 
may not be reversed without altering the position of the pulleys. 
When the shafts are close together or at right angles in the same 
plane, a mule stand carrying two mule pulleys is used and placed 
as shown in the illustration. (Fig. 1955/.) 

1956. Lining up Shafting. There are several methods of 
securing the accurate alignment of a line of shafting, the best way 
being to survey it with the transit. The line is established and 
marked by scratches on the heads of tacks, at each end and at 
intermediate distances on the floor below the hangers. A plumb 
line dropped from the shaft at frequent intervals is used to secure 
the alignment of the shaft with the line of tacks; this being 
effected, the shaft is made level by taking level readings on a 
rod placed in contact with the bottom of the shaft. 

If no transit is had, the line may be established with an ordi- 
nary chalk Une and the leveling effected by establishing a level 
on the top of nail heads driven in the floor, and then using a rod 
just long enough to touch the nail head on the floor and the under- 
side of the shaft. A long straight edge and a good level — which 
should be reversed for every reading — are all that are needed to 
secure the level on the nail heads. 

1957. Belts and Belting. A belt is the band, usually leather, 
which passes over two pulleys and transmits the motion and 
power from one to the other. An endless belt is one in which 
no joint or lacing appears, the joint being cemented in a manner 
similar to the rest of the belt. 

Belts are usually made of oak-tanned cowhide leather, though 
there are belts made of rawhide, cotton and rubber. The basis 
of strength in rubber belting is cotton duck, the plies of which 
can be increased to resist any required tensile strain, the rubber 
coating being pressed onto this duck Base. That portion of the 
hide best adapted for belting is what is known as the butt; the 
head, neck, shoulders and flanks, being uneven in texture, are not 
at all suited for belting. Strips the width of the belt are cut 
from these butts and cemented together by lap joints, to the 



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448 ENGINEERING AND SHOP PRACTICE 

required length. When one thickness of belting is used, it is 
known as single-ply; when two thicknesses are cemented together, 
it is two-ply; and when three are used, three-ply. 

In some instances fast running belts, over 4000 feet per minute, 
are perforated; the perforations prevent air cushions from forming 
between the belt and pulley and allow the belt to run looser with 
less strain upon the bearings. 

Great care should be taken in the selection of the leather used 
in the manufacture of the belt, as upon the quality and firmness 
of it depend the life and wear of the belt. Good oak bark tanned 
leather requires about one hundred and twenty days in the 
tanning process from the dry hide to the finished product. Belt- 
ing butts are usually stuffed with cod oil and pure beef tallow to 
preserve the leather and render them suitable for the transmission 
of power, after which they are stretched and smoothed. 

When it is necessary to run a leather belt in wet or damp 
places, or in the proximity of acids or dyes, some one of the 
many waterproofing materials on the market should be used. 
These generally increase the adhesive power, prevent slipping 
and render the belt soft and pliable. Belt dressings are supposed 
to perform the above functions with the exception of the water- 
proofing. 

Belts, unless endless, are generally joined by rawhide strips 
termed laces, though they are sometimes laced with a special 
alloy wire. Hooks are also used. 

1958. Belt Lacing. In laying out a splice, the try-square 
should always be used in order that the ends of the joint may be 
cut at right angles to the edge of the belt. Many an otherwise 
good splice is ruined by the neglect of this caution. The four 
styles of lacing shown by the drawings are indicative of good 
practice and will be discussed in the order of their arrangement. 

The double-laced splice shown in No. 1, 1958a is often used 
instead of the single-laced splice similar to it. In this, as in all 
other splices, the lacings should be so arranged as to draw and 
keep the edges in line, and the lacings should not be crossed on 
the side of the belt that runs next the pulley. No. 1 gives a 
strong joint but not a lasting splice for the reason that any ex- 
cessive service produces premature wear on the outer layer, which 
takes the bulk of the wear and tear of the lace at A and fi, caus- 
ing them, when worn thin, to tear out. To overcome this diffi- 



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449 



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450 



ENGINEERING AND SHOP PRACTICE 



culty the style of lacing shown in No. 2, 1958a is oftentimes used; 
instead of using one end of the lace and working over and over 
through the holes, two ends of the lace are taken and one is drawn 
in over the other from the opposite side as indicated. With this 
arrangement, parts of the two laces come in contact with the 
pulleys, instead of one as before. 



Pulley Side 




Outside 




Outside 



Pulley Side 



V 




Pulley Side 

Fig. 19586. 



Outside 

- Other Belt Lacings. 



No. 3 is what is termed the hinge splice and may be made 
double with a double row of holes or with but a single row as 
shown. This makes a flexible joint and one that will readily run 
over a small pulley. The lacing, as will be seen, is passed from 
the hole down between the ends of the belt, the corners of the 
ends of which have been previously rounded. This joint is some- 
times used for its economy in belt lacing, a short piece going a 
considerable way. 

No. 4 is an excellent lace, makes an excellent splice and is 
used chiefly for heavy work with belts of average width. In its 



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451 



free distribution of the stress, bringing the pull on as many differ- 
ent points as possible, it is better than many of the other styles 
in use. As in the other instances, the holes and the ends of the 
joint should be laid off with the try-square. Care should be 
taken to get each hole into the position corresponding with its 
mating hole on the other half of the joint. The sketch shows the 
outside of the lace. Commence lacing from the center and pro- 
ceed as indicated. 

Another series of belt lacings is shown in Fig. 19586. 

1959. Horse-power Transmitted by Leather Belting. 

Table Giving the Horse-Power Transmitted by Leather Belts one 
Inch Wide, Considering the Effects of Centrifugal Force, so that 
THE Tension on Belt is Constant at all Speeds 



Speed in Feet 
per Minute 


Sinfrle 
A' thick 


Double 
r thick 


Triple 
ft* thick 


Four-ply 
r thidc 


100 


.14 


.24 


.33 


.44 


200 


.27 


.48 


.67 


.88 


300 


.41 


.73 


1.00 


1.32 


400 


.54 


.96 


1.33 


1.75 


500 


.68 


1.21 


1.66 


2.19 


600 


.81 


1.44 


1.99 


2.62 


700 


.95 


1.68 


2.31 


3.05 


800 


1.08 


1.93 


2.64 


3.48 


900 


1.21 


2.15 


2.96 


3.90 


1000 


1.34 


2.38 


3.28 


4.32 


1100 


1.47 


2.61 


3.59 


4.73 


1200 


1.60 


2.85 


3.90 


5.14 


1300 


1.73 


3.07 


4.21 


5.55 


1400 


1.86 


3.30 


4.51 


5.94 


1500 


1.98 


3.53 


4.81 


6.34 


1600 


2.10 


3.73 


5.10 


6.72 


1700 


2.23 


3.94 


5.39 


7.10 


1800 


2.34 


4.15 


5.67 


7.47 


1900 


2.46 


4.35 


5.94 


7.83 


2000 


2.58 


4.56 


6.21 


8.18 


2200 


2.80 


4.94 


6.73 


8.85 


2400 


3.01 


5.30 


7.21 


9.51 


2600 


3.21 


5.65 


7.67 


10.09 


2800 


3.40 


5.97 


8.09 


10.64 


3000 


3.58 


6.25 


8.47 


11.14 



Table continued on page 452. 



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452 



ENGINEERING AND SHOP PRACTICE 



Speed in Feet 
per Minute 


Single 
A*' thick 


Double 
r thick 


Triple 
ft'tfoch 


^^?l^ 


3200 


3.74 


6.52 


8.80 


11.58 


3400 


3.89 


6.74 


9.10 


11.96 


3600 


4.03 


6.95 


9.35 


12.28 


3800 


4.14 


7.12 


9.55 


12.57 


4000 


4.24 


7.26 


9.70 


12.73 


4200 


4.33 


7.36 


9.79 


12.84 


4400 


4.39 
4.43 
4.45 


7.42 
7.44 1 


9.83 


12.88 


4600 


9.80 
9.72 
9.56 


12.84 


4800 


7.42 
7.37 


12.71 


5000 


4.45 


12.50 


5200 


4.43 


7.26 


9.34 


12.20 


5400 


4.38 


7.10 


9.05 


11.80 


5600 


4.31 


6.92 


8.69 


11.30 


6800 


4.21 


6.65 


8.25 


10.70 


6000 


4.09 


6.35 


7.73 


10.00 


6200 


3.94 


6.01 


7.13 


9.19 


6400 


3.76 


5.58 


6.44 


8.26 


6600 


3.56 


5.11 


5.67 


7.22 


6800 


3.32 


4.57 


4.80 


6.06 


7000 


3.05 


3.98 


3.84 


4.77 


7200 


2.75 


3.31 


2.79 


3.36 


7400 


2.42 


2.60 


1.64 


1.82 


7600 


2.05 


1.82 


0.39 


0.14 


7800 


1.65 


0.95 






8000 


1.21 








8200 


0.74 








8400 


0.23 









HP^ JT- 0.012 i V^) V 



t 

T 
T- 0.012 tV* ■• 
T 

V '. 



500 

« thickness of belt in inches. 
= working tension of belt. 
= effective tension of belt. 
- 45 lbs, 80 lbs., 110 lbs., 145 Jbs. 
■- velocity. 



Fig. 1959. 

For belts more than one inch wide, multiply the width by the 
value in the table. 



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CHAPTER XX 

MOTOR DRIVES AND MOTOR-DRIVEN MACHINE TOOLS 

2011. Advantages of Motor Drives. The chief advantages 
of a system of individual motor drives for machine tools, etc., 
aside from the great economy of such a system, are the absence 
of overhead shafting; giving better light and crane service; its 
convenience for detached buildings; the independent location of 
machines; the speed control and easy manipulation and as an 
inevitable result of these conditions its introduction leads to new 
methods, which not only secure a greater output but also an 
increase of excellence in the product. Chas. F. Scott says: "The 
introduction of the motor into the machine shop has resulted in 
new methods of applying power and controlling it, which have, 
not only increased the output of the tool, but have reacted upon 
its design so that new methods have been worked out leading to 
radical advances. It may be noted that in the rapid and radical 
change which has taken place in machine shop practice, high- 
speed tool steels and motor drives are the important factors, 
though the principal features which enable the motor to play so 
important a role in this change are mechanical rather than elec- 
trical, viz., speed regulation and control." 

The accompanying chart (Fig. 2011, page 454) illustrating the 
principal advantages and various methods that may be adopted 
for driving machine tools was made in 1903 by Dodge and Day. 

2012. Relative Costs of Equipment. As the total cost of 
power in a large factory is a very small percentage of the entire 
cost of production — from 2% to 5% — motor drives gained but 
little popularity with manufacturers until it was demonstrated 
that, besides reducing the cost of power, with them it was possible 
to reduce the cost of labor, to increase the output, to improve 
the product, to reduce power demands and to use greater power 
more effectively. 

Regarding the first cost of installation, G. M. Campbell, in an 

453 



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ENGINEERING AND SHOP PRACTICE 




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MOTOR DRIVES AND MOTOR-DRIVEN MACHINE TOOLS 455 

article on "Machine Shop Practice," read before the Engineering 
Society of Western Pennsylvania, makes the following remarks: 
"It may be readily proved that for any tool in which variation 
in speed is required, large or small, that the installation of an 
individual motor drive with 10% speed increments will be an 
economical investment. The time is coming when practically 
every metal-working tool where speed changes or changes in 
material are required, will be, in an up-to-date machine shop, 
equipped with its own individual motor and at practically the 
price of the present tools." Until recently it was generally 
considered that the individual motor drive was more expensive 
than the group drive system. However, a careful inspection of 
the report by the Committee of the Master Mechanics' Association 
regarding the shops of the Lake Shore Railroad shows that just 
the reverse is true, as will be seen from the following extract: 

Lake Shore and Michigan Southern Railway Collingwood Shops 
estimated cost for individual drive 

103 Motors $12,340.00 

Wiring 103 Motors @ $18.30 1,884.00 

Wiring 242i H. P. @ 5.40 1,164.00 

$15,388.00 

COST FOR GROUP DRIVING 

11 Group Motors $4,550.00 

Wiring 11 Motors @ $18.30 201.30 

Wiring 202 i H.P. @ 4.80 972.00 

Countershaft, Line, Belt, Pulleys, etc 6,667.00 

Belting 3,881.00 

$16,271.30 

The result is even more favorable, says the report, to the 
individual drive than appears in the estimate, for the roof con- 
struction of the shop would have had to be appreciably heavier 
to support the line and countershafting. Nor does any item in 
the report cover the cost of belt shifters and the erection of the 
belting for the group driving which, for 103 tools, is quite an 
expense. 

2013. Economy of Motor Drives. As practical evidence of 
the advantage and economy of electric driving, the Westinghouse 
Electric Co. cite a case where thirty steam engines of 1375 total 
horse-power were supplanted by fifty-seven motors of 1065 total 



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456 ENGINEERING AND SHOP PRACTICE 

horse-power for machine shop driving and where the average 
daily saving in steam was 41.6%; and of combustible, 31.2%. 
In other cases, according to the American Machinist, electric 
driving has reduced by 50%. the cost for engineer, coal and w^ater; 
the fuel account, 20%, and the cost of power, 44%. The gross 
saving was 30% with direct-connected motors and 22% with 
belted or geared motors. 

Concerning the economy in the operation of motor drives, 
the results that obtained at the Pittsburg and Lake Erie Shops 
during the year 1904 are given as being typical. For this year 
the average horse-power taken by all machine-tool motors was 
about 200 during the working hours. The average power con- 
sumption at present, 1906, is about 300 or 30% of the horse- 
power rating of the 83 motors, the average horse-power of each 
being 12.05. Only 17.3% of the power-house output was used 
by the machine tools, it being 38.71%. of the total electric power; 
the lighting consumed 24.9% while the heating and ventilating 
motors took 23.78%. 

A tabulated horse-power consumption for each type of work 
is as follows: 

Variable Speed Tools 39.71% 

Constant " " 26.80% 

Blast Fans 28.44% 

Cranes 5-05% 

Total, 100.00% 

The total cost of power for the machine tools and cranes, 
exclusive of maintenance, was $2,662.66. The power-house 
capacity is 600 kilowatts and with an overload rating of 25% 
it would be 750 kilowatts. The motor rating for the 83 motors 
above mentioned was 1000 horse-power. 

It will, no doubt, be surprising to note that the power losses 
which obtain when all machines are running light may reach or 
even exceed the average power consumption throughout the 
working days. To illustrate this point, the following diagram 
(Fig. 2013) is taken from an excellent article by Mr. Campbell on 
** Power Required by Machine Tools." This paper was read, 
February, 1906, before the Engineers' Society of Western Penn- 
sylvania. The good results obtained in the Pittsburg and Lake 
Erie Shops may be indicated from the fact that where formerly 



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MOTOR DRIVES AND MOTOR-DRIVEN MACHINE TOOLS 457 



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458 



ENGINEERING AND SHOP PRACTICE 



it was possible to overhaul five to seven locomotives each month, 
now fourteen to twenty are overhauled and the new shops are 
considered such an excellent investment that it is estimated that 
they will have paid for themselves, including first cost and 
interest, in ten years or less. 

Motors for Shop and Machine Tool Driving 

2021. Constant-speed Motors. Under this heading are classed 
motors whose average variation from no load to full load is 
not over 5%. Their general characteristics, as may be seen 
from the plotting of heavy lines in the diagram — "Typical 
Curves for Shunt and Compound Motors" (Fig. 2021) — are as 
follows: In all but the synchronous motor — which gives abso- 
lutely a constant speed if the cycles of the circuit upon which it 
operates remain constant — the speed is approximately constant, 
falling slightly with the load. The torque and brake horse-power 
are closely proportional to the armature current, while the motor 
automatically adjusts itself to give constant speed as the different 
loads come on it. 

Mr. Day remarks that the constant-speed motor, particularly 
of the alternating type, is so simple in character that we naturally 
turn to it as the possible solution of the problem of direct-con- 
nected machine drives. He states that it lacks two great essen- 
tials, viz., ease of handling and speed regulation, and that all 
attempts to supply these shortcomings by mechanical means 
have, so far, proved unsatisfactory. His statement that the 
induction motor is merely a source of power, just as the line 
shaft, carries with it the inference that it is inflexible as to speed 
regulation; however, W. I. Schlichter, in a paper before the 
A. S. M. E., June, 1903, presents several successful methods of 
controlling and varying the speed of alternating-current motors. 

The different types of motors are classified by W. Edgar Reed 
as follows: 

Continuous I 
Current I 



Constant Speed 
Variable Torque 



Shunt Wound 



Alternating 
Current 



Induction 



Single-phase 
Poly-phase 



Wound Rotor 
Short-circuited 
Rotor 



[Synchronous { p "j^'^^^^ 



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MOTOR DRIVES AND MOTOR-DRIVEN MACHINE TOOLS 459 



Fig. 2021. — Typical Curves for Shunt and Compound Motors. 



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460 



ENGINEERING AND SHOP PRACTICE 



Their characteristics are classified in the following table: 

. «T J f Characteristics noted on diaeram; normal speed may bo 
Shimt Wound 1 • j u u • c u * Lu 

I varied by changes m field strength. 



Induction 



Single-phase 



Poly-phase 



Built in small sizes and for operation on 
lighting circuits. Small starting torque, 
large line current to start — must be brought 
up to nearly full speed before load is thrown 



Adapted for polyphase lighting circuits. Start- 
ing current for developing full load; t'Orque 
only slightly in excess of full load current. 
Running characteristics similar to those of 
shunt-wound motor except that it has but 
one definite speed. 



Synchronous 



Absolutely constant speed, no starting torque; not self- 
starting with load. Must have continuous current avail- 
able for field excitation. Used principally in large sizes. 



2022. Variable or Adjustable Speed Motors. In general, this 
class of motors is designed to give automatically a wide range of 
speeds for the different torques and outputs required of it. They 
have no definite horse-power rating but are generally rated at 
the horse-power they develop for one hour within a stated rise 
in temperature; the rises most often selected being 40°, 60° or 
75° Centigrade. The selection of a suitable motor of this type 
should depend largely upon the maximum torque required of 
it and this should be developed without undue sparking or 
heating. 

Plotted on the same diagram (Fig. 2022a) for comparison are 
the general characteristics of this class of motors; the one on the 
left gives characteristic data either for the series-wound continuous 
or the single-phase, series-wound alternating-current motor, while 
the one on the right shows the same data for the polyphase 
induction motor. 

The different types are thus divided by W. Edgar Reed in the 
table: 



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MOTOR DRIVES AND M01X)R-DRIVEN MACHINE TOOLS 461 



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MOTOR DRIVES AND MOTOR-DRIVEN MACHINE TOOLS 463 



Variable Speed 
Variable Torque 



Continuously . .„. , 
p j Series Wound 



Alternating, 
Current 



Single-phase, Series Commutator 

n 1 1- T J A- ,/ Wound Rotor 
I Poly-phase Induction M au _* • •* j t, ^ 
•' '^ L Short-circuited Rotor 

A classification of the characteristics of the variable or adjust- 
able speed motors are as follows: 



Series Wound 



Single-phase 
Series Commu- 
tator 



Poly-phase In- 
duction 



40% to 75% speed increase with half load. Speed varies 
inversely as load running at such a speed with no load 
that they are liable to burst. Torque and brake-horse- 
power increase as the current increases. 

Some of the general characteristics of direct-current mo- 
tors. Single-phase series motors excellent for railway 
and similar classes of service. 

10% to 15% speed increase with halMoad. Speed varies 
inversely as the load. Any torque at any speed over 
a wide range. Torque maximum at starting, decreas- 
ing uniformly as the speed increases except at low 
speeds. See plotting for torque speed curves, Fig. 
2022b. 



2023. Compound Motors. Because the compound motor has 
two independent field windings, one a shunt and the other a 
series, thp shunt being connected in a similar manner to the 
field winding of the simple shunt motor and the series winding 
carrying the armature current, it possesses some of the charac- 
teristics of both the constant and variable speed motors. It has 
a greater maximum starting torque than the constant-speed and 
a lesser than that of the variable-speed motor; and, while the 
current for a given starting torque is less than that for the con- 
stant-speed motor, it is greater than that for the variable-speed 
motor. 

The characteristic curves in dotted lines were plotted, for 
comparison, on the diagram "Typical Curves for Shunt and 

'Given in both classifications. "A slight diflFerence in design of the 
short-circuited rotor motor will change a constant-speed motor requiring 
fairly large current from the line at starting, to a variable-speed motor re- 
quiring much less current from the line for tho same starting torque." The 
wound rotor motor may aljo be easily changed from one class to the other. 



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464 ENGINEERING AND SHOP PRACTICE 

Compound Motors" in Sec. 2021, Fig. 2021. These curves were 
taken from tests upon the same motor, first with shunt and 
series windings both operating, and second with only the shunt 
winding in operation. Compound motors have a fixed no-load 
speed, the speed varying inversely as the load, i.e., high speed at 
a light load. 

The different kinds of motors having characteristics of the 
compound type are thus tabulated by Mr. Reed, who states that 
'Hhe so-called compound motor is generally of the continuous- 
current type but that polyphase induction motors of the short- 
circuited or wound rotor types are made and these have nearly 
the same operating characteristics." 



Compound Motors 



Continuous Current | Compound Wound 

{Induction 
^ , ^ [Short-circuited Rotor 
P^^y-P^lWound Rotor 



This motor is especially valuable for driving reciprocating 
machinery, planers, shapers, printing presses, etc., because it 
holds in check the surge of current from the line at the in- 
stant of reversal, at the time when the maximum torque is 
required. 

2024. References to Other Data. For other information 
regarding electric motors the student is referred to that portion 
of Chapter 19 on "Power Transmission'' which deals with electric 
transmission, and especially to Sections 1915, 1916, 1917 and 1918. 
Should a more exhaustive study of motors and motor driving be 
desired, much valuable information may be had from the articles 
on **Feed Characteristics and the Control of Electric Motors," by 
Chas. F. Scott, which appeared in the Engineering Magazine of 
April and May, 1906; a paper by W. Edgar Reed on "Electric 
Motors and Their Application," published in Vol. 21, 1905, of 
the Proceedings of the Engineers' Society of Western Pennsyl- 
vania; and to two papers by G. M. Camp])ell which appeared in 
the Proceedings of the same society, one in November, 1905, and 
the other in February, 1906; one dealing with " Machine Shop 
Practice," and the other with "Power Required for Machine 
Tools"; and again, to a paper by Robert T. Lozier, read before 
the New York Electrical Society and distributed by the Bullock 



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MOTOR DRIVES AND MOTOR-DRIVEN MACHINE TOOLS 465 

Electric Mfg. Co., on the "Electrical Operation of Modern Machine 
Tools and Machinery." 

Working Applications of the Various Motors 

2031. On the Choice of a Motor. In general, it may be stated 
that more than one type of motor may be used to perform a 
given kind of work, and conditions of electrical distribution alone 
may determine the selection. It is very important, however, to 
know all the conditions required of the service as special condi- 
tions ofttimes exert a preponderating influence in the choice of 
a motor. 

2032. Constant-speed Service. The purpose of the following 
list is to give a few general applications of drives requiring the 
use of constant-speed motors: 

Wood- working Machinery, Lathes, Circular and Band Saws, etc. 

Fans, Blowers, Air Compressors. 

Such Machine Tools as have Rotary Motion, Lathes, Drills, 
Milling Machines, Boring Mills, etc. 

High and Slow Speed Centrifugal and Reciprocating Pumps. 

Shoe-making Machinery. 

Laundry Machinery. 

Hydraulic Elevators. 

Line Shafting which requires a fairly constant speed with few 
stops. 

2033. Variable or Adjustable Speed Service. Because of the 
tendency in the series motor to run away at low or no loads, and 
because of temperature, sparking and other conditions in other 
types of this class, variable-speed motors find their general appli- 
cation in cases where the motors are always under control of the 
operator. In this class of service are found : 

Street Railway Motors. 
Locomotives. 

Cranes, Hoists, Elevators, etc. 

Used for service requiring frequent stops and high-speed 
averages. 

2034. Drives and Tools Requiring Compound Service. As 
has been previously stated, this motor finds its largest application 
in driving reciprocating machinery where a full load is thrown 
suddenly and intermittently on the machine. Under this class 
of service are placed : 



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468 ENGINEERING AND SHOP PRACTICE 

Machine Tools having Reciprocating Motion. 
Planers, Shapers, Blotters and Presses. 
Punches, Shears and Presses. 
Hoists, Elevators and Cranes. 
Bending and Straightening Rolls. 
Printing Presses. 
Crushers, etc. 
Roller Beds. 

Speed Regulation 

2041. Speed Ranges. As is evident, to even the novice, 
machine-tool work requires speed variation for economic produc- 
tion. How much or through what range and what proportion is 
to be taken by the motor and what part can be had in the tool 
itself are the problems. A motor can be made to operate at any 
speed between and the maximum, but it becomes abnormally 
large for great ranges, as the speed is a direct function of the 
power: Electric manufacturers say that the practical range is 
6 or 7 to 1, though this may be increased to 10 to 1 without 
difficulty. Generally speaking, from the shop man's standpoint, 
it seems best with the present motors and tools not to exceed 
4 to 1 in the motor, obtaining the rest of the variation by runs of 
gears, though just what speed range to give the motor cannot be 
stated for all conditions. 

With a lathe having a spindle-speed variation say of 26 to 1, 
the variation could be obtained with four runs of gears and a 
speed variation in the motor of 3 to 1. With the gears, *'run 2" 
would give three times 1; '^run 3,'' three times 2; and *'run 4,*' 
three times 3, and as this is a range of 3009t, the motor is given 
3 to 1 and operates as follows: starting with the lathe running 
with **run 1 '* and the motor at initial speed, the speed may be 
brought up gradually by any increment until it is three times 
the initial speed; ''nm 1" is now dropped out, *'run 2'' thrown 
in and the motor brought back to its initial speed, giving the next 
speed to the spindle above that with *'run 1 '* and so on through 
the entire range. 

Speed increments of only 5% or less may be necessary, but for 
the regular nm of work increments of 10^^^ will be found suitable 
and with this increment the number of controller points obtained 
by the formula given by G. M. Campbell will be: 



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MOTOR DRIVES AND MOTOR-DRIVEN MACHINE TOOLS 467 

Speed Range of Motor « 1.1""'. The off-point b?ing counted as 

one (n being the total number) 



Speed Range 




Controller Points 


3 


» 


14 


4 


s= 


17 


5 


= 


19 


6 


s 


21 



This gives the forward points and to it must be added the 
required number of backward points, usually one third or half 
the number of forward ones. 

2042. Speed Control. As a rule, the speed of any motor is 
dependent upon two factors, viz., the field strength of the motor 
and the electro-motive force or voltage applied to the armature; 
this being the case, a constant speed results if the voltage and 
the field strength are a constant, though the load may vary. 
Again, a constant speed results if a decrease in either element is 
accompanied by a corresponding increase in the other, and further- 
more it is seen that a variable speed would result from a variation 
of either element alone or an unequal variation in both. 

There are several methods of speed control, usually variations 
of two general types: (1) Speed control by field strength and 
(2) speed control by armature voltage. In Bulletin No. 1007, 
the Bullock Electric Mfg. Co. give the three methods herewith, 
making the objections noted after each. They only indicate 
practice in a general way and nothing is said here in reference to 
the Bullock Electric Mfg. Go's patented system of multiple- 
voltage control which is a very successful and efficient one. 

(1) Speed control by field strength: Changing the total amount 
of magnetism — the armature conductors and impressed volts 
remaining a constant. With this method the two governing 
factors are opposed to each other; i.e., increasing the number of 
conductors on the armature to avoid trouble at slow speeds 
gives just the opposite effect at high speeds. A speed range of 
only 2 to 1 may be obtained and the machine sizes are abnormal 
for the horse-power output; a 2 to 1 range necessitating a motor 
four times the required size. 

(2) Speed control by armature voltage: Changing the in- 
pressed electro-motive force at the motor terminals by connecting 
the armature across the lines carrying different voltages, these 
voltages ])eing maintained a constant direct from the generator. 



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468 ENGINEERING AND SHOP PRACTICE 

This system is on a par with using resistance in the armature 
circuit to vary the electro-motive force as regards the size of the 
motor. 

(3) Changing the number of poles and at the same time the 
armature connections to correspond. With this method an 
eight-pole machine would give, approximately, }, i and full 
speed; a sixteen-pole machine, i, J, i and full speed. There are 
many serious defects to this system such as loss of torque, when 
the poles are reversed, stopping, etc. 

After discussing at length the different methods, Pres. Chas. 
F. Scott of A. I. E. E. makes the following statement: "A com- 
parison of the foregoing methods of speed control shows several 
points in favor of control by variation of the strength of the 
shunt field, when adjustable speeds are desired, which shall be 
constant, independent of load variations. The motor and control 
devices are simple; the supply circuit is of the simplest kind 
without special generators or additional wires. The current is 
always minimum, as no low voltages are used which would require 
a greater current for a given power." 

In spite of this fact, the multiple-voltage system has met with 
great success in a number of large machine shops. 

2043. Speed Control Relations. The following definite rela- 
tions obtain between the voltage, current, speed and torque, and 
are given here in order that a better understanding may be had 
regarding speed control. 

(1) Horse-power is proportional to speed X torque. 

(2) Power is proportional to E.M.F. X current. 

If E.M.F. be constant the speed is a constant. 

(3) Therefore torque, H.P. and current vary together. 

(4) If the load be doubled, both the torque and current are 

doubled; under these conditions it follows that the 
torque and current are proportional. 

(5) If the E.M.F. applied to the armature be varied, the 

speed changes in like proportion. 

(6) With a definite, constant field strength the speed is pro- 

portional to the applied E.M.F.; and the torque is 
proportional to the current. 

2044. Systems and Wiring. The different systems of wiring 
are the single-voltage or 2-wire, the two equal voltage or 3-wire 
and the multiple- voltage or 4-wire. In all the systems the size 



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MOTOR DRIVES AND MOTOR-DRIVEN MACHINE TOOLS 469 

of motor required is about the same. A 2-wire installation already 
in service can incorporate without any trouble any number of 
variable-speed, single-voltage motors. 

The 3-wire system is a cross between the multiple voltage and 
2-wire with part of the good and part of the bad points of each. 

In brief, the multiple voltage system, which is a type of speed 
control by armature voltage, consists of several sources of current 
supplied at different voltages, each differing by a fixed ratio. 
We may have a 3-wire system which has 220 volts on two of its 
wires and 110 volts between each of these and the middle wire, 
which gives us two speeds at a ratio of two to one: then again, 
we may have a 3-wire system with unequal voltages; for example, 
80, 160 and 240 volts, dividing the maximum voltage into thirds 
instead of halves as in the former instance. Or we may have a 
4-wire system between which the following voltages are main- 
tained: 60, 80 and 110 volts respectively. The different voltages 
obtained with this arrangement are 60, 80, 110, 140, 190 and 250. 
Such an arrangement with a small range of shunt-field regulation 
could be given a speed range of about 6i to 1. 

Speaking of the multiple- voltage system Mr. Scott says: 
"The principal advantages in the use of the multiple- voltage 
system involving a considerable number of voltages are that less 
range of speed is necessary in the field control." And as before 
stated he goes on to recommend the control by the variation in 
strength of the shunt field. For reciprocating machine tools, 
the multiple-voltage system is undoubtedly advantageous. An- 
other strong point in favor of this system is that standard motors 
are used. 

Horse-power Requirements 

2051. Motor Ratings. The plottings on the diagram here- 
with (Fig. 2051) are taken from Mr. Campbell's paper and indicate 
how little reliance may be placed upon the manufacturer's rating 
of a motor. A '*5 H.P. Motor" means very little unless we 
know the conditions under which it operates or on what particular 
basis the rating is made. 

From the diagram it may be seen that a 5 horse-power motor 
may weigh (and cost somewhere in proportion) from 360 to 1600 
pounds. And again that one might pay for and receive a 30 horse- 
power motor when the rating called for but a 5 horse-power motor. 



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470 ENGINEERING AND SHOP PRACTICE 



speed Variation 
Fig. 2051. — Weights of Variable -speed Motors. 



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MOTOR DRIVES AND MOTOR-DRIVEN MACHINE TOOLS 471 

2052. Power Requirements of Reciprocating Tools. The 

selection of a motor for reciprocating machine tools such as 
planers, shapers, punches and shears is almost independent of 
the cut taken and depends largely upon the machine itself. The 
following data are taken from a test made on a 60'' planer. During 
the cutting stroke, the horse-power reading was 3.9; reversing to 
return stroke, the power ran up to 19. On the return stroke the 
reading, was 6.3, while in reversing to the cutting stroke a reading 
of 27 horse-power was had. The readings were taken with the 
machine running light, the speed of the cutting stroke being 25 
and of the reverse stroke 60. This machine was driven by a 
20 horse-power motor. Readings were taken on the power 
required for punches, the horse-power jumping from .6 when 
running light, to 24 horse-power while punching If holes in a 
l" plate. It is evident that this class of work requires some sort 
of a balancing device to oflfset such fluctuations. To this end, 
motors driving this class of service should be equipped with a 
fly-wheel of large diameter and heavy rim, to assist the motors 
at the instant of reversal. The fly-wheel may be placed some- 
w^here in the driving mechanism, but it is vastly to be preferred 
mounted on the motor shaft. 

2053. Campbell's Formula. In his investigations, Mr. Camp- 
bell discovered t-hat, other conditions being the same, the power 
taken by the machine, after allowance is made for friction losses, 
will vary approximately as the speed and cut and therefore as 
the weight of metal removed; consequently, in fitting motors to 
tools, due allowance must be made for high speeds and maximum 
cuts, bearing in mind the coming universal use of high-speed 
tool steels and increase in rigidity of machines. Mr. Campbell's 
formula for the power absorbed in cutting is thus stated: 

II. P, = KWy where H.P. = Horse-power; /C = a constant 
depending on the kind and grade of material; and W = Weight 
of Metal, pounds removed per minute. 

Values of K may be taken as follows: 

K = 2.5 for hard steel. 

= 2.0 for wrought iron. 

= 1.8 for soft steel. 

= 1.4 for cast iron. 

In comparing the results obtained by this formula with the 



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472 ENGINEERING AND SHOP PRACTICE 

actual horse-power noted in a large number of instances and on 
a wide range of work, some wide variations were noted; but the 
agreement in general was sufficiently close to show that the 
formula is a reasonable one for arriving at the approximate 
horse-power required for doing the actual work. 

2054. Horse-power Required to Remove Chips of Given 
Area. The charts, four in number, give the horse-power required 
to remove chips of a known area (depth of cut times feed) at the 
ordinary rates of speed. The horse-power obtained will be found 
ample and the speed range and area of the chip as plotted are 
sufficient to give data for even the heaviest cuts with high-speed 
steels. The method of using these diagrams, Figs. 2054a, 6, c 
and d, is: It is desired to know what horse-power is required to 
remove, from soft steel, a chip y\* X J'' (^^" deep X V feed) at a 
speed of 40 feet per minute. On the chart for soft steel find the 
curve marked 40 feet, follow this down until it intersects the 
^jr^ abscissa. The reading directly below, 8.54, gives the horse- 
power required to remove a chip ^^'^ square. § of this value, of 
course, gives the horse-power required to remove the chip ^^ x i" 
or 5.7 horse-power. These horse-powers will be found ample and, 
though calculated by Campbell's formula, are about the same as 
when calculated by Mr. Pomeroy's formula which appeared in 
the General Electric Review, 1908. 

Horse-power = FxDx f.p.m, Xl2X NxC 

where F = feed in inches. 
D = depth of cut. 
f.p.m. = feet per minute. 

A^ = number of tools cutting. 

C = a constant depending upon the material. 

The horse-powers in the table may be obtained by giving C 
the following values: Hard steel, C = .71; wrought iron, C = .51; 
soft steel, C = .51; cast iron, C = .37. 

The tables (Figs. 2054aa, 66, cc and dd) accompanying the 
charts, not only give the horse-power required, but also the weight 
of metal removed per minute for the given cut and speed. 



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MOTOR DRIVES AND MOTOR-DRIVEN MACHINE TOOLS 473 



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MOTOR DRIVES AND MOTOR-DRIVEN MACHINE TOOLS 475 



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MOTOR DRIVES AND MOTOR-DRIVEN MACHINE TOOLS 477 



H0R8S-POWER Required 


AND Weight of Chips at 


THE 


Various Speeds 


Size 

of 

Chip 


10 Feet 


ao Feet 


30 Feet 


40 Feet 


so FEEt 


60 Feet 


80 Feet 


100 Feet 


H.P. 


Wgt. 


H.P. 


Wgt. 


H.P. 


Wgt. 


H.P. 


Wgt. 


H.P. 


Wgt 


H.P. 


Wgt. 


• 
H.P. 


Wgt 


H.P. 


Wgt 


VSq- 


.32 


.13 


.64 


.26 


.96 


.39 


1.3 


.62 


1.6 


.65 


1.9 


.78 


2.6 


1. 


3.2 


1.3 


•Sq. 


1.3 


.63 


2.6 


1.1 


3.9 


1.6 


6.2 


2.1 


6.6 


2.7 


7.8 


3.2 


10.4 


4.2 


13. 


5.3 


A'Sq. 


3. 


1.2 


6. 


2.4 


9. 


3.6 


12. 


4.8 


16. 


6. 


18. 


7.2 


24. 


9.6 


30. 


12. 


'Sq. 


6.3 


2.1 


10.6 


4.3 


16.9 


6.4 


21.2 


8.4 


26.5 


10.5 


31.8 


12.6 


42.4 


16.8 


53. 


21.3 


11' Sq. 


8.3 


3.3 


16.6 


6.6 


24.9 


10. 


33.2 


13.2 


41.5 


16.6 


49.8 


19.8 


66.4 


26.4 


83. 


33.2 


's3. 


12. 


4. 


24. 


9.6 


36. 


14.3 


48. 


18.8 


60. 


23 5 


72. 


28.2 


96. 


37.6 


120. 


47.8 


A'Sq. 


16.2 


A.5 


32.4 


13. 


48.6 


19.6 


64.8 


26. 


81. 


32 6 


97.2 


39. 


129.6 


52. 


162. 


65.1 


Y'sS. 


21.2 


8.5 


42.4 


17. 


63.6 


26.6 


84.8 


34. 


106. 


42.6 


127.2 


61. 169.6 


68. 


212. 


86. 



Fig. 2054aa. Hard Steel. 



A*Sq. 


.26 


.13 


.5 


.26 


.76 


.39 


1. 


.62 


1.3 


.66 


1.6 


.78 


2. 


1. 


2.5 


1.3 


•s3. 


1. 


.62 


2. 




3. 


1.6 


4. 


2.1 


6. 


2.6 


6. 


31.2 


8. 


4.2 


10. 


6.2 


Ik'Sq. 


2.3 


1.1 


4.6 


2.2 


6.9 


3.3 


9.2 


4.4 


11.5 


5.6 


13.8 


6.6 


18.4 


8.8 


23. 


11.7 


"Sc^. 


4.2 


2.1 


8.4 


4.2 


12.6 


6. 


16.8 


8.3 


21. 


10.4 


25.2 


12 6 


33.6 


16.6 


42. 


20.8 


1 'Sq. 


6.5 


3.3 


13. 


6.4 


19.6 


9.6 


26. 


12.8 


32.6 


16. 


39. 


19.6 


52. 


26. 


66. 


32.6 


•Sc^. 


9.4 


4.7 


18.8 


9.4 


28.2 


14.1 


37.6 


18.8 


47. 


23.5 


56 4 


28.2 


75.2 


37.6 


94. 


47. 


r-is: 


12.8 


6.4 


26.6 


12.8 


38.4 


19.2 


51.2 


25.6 


64. 


32. 


73 8 


384 


1024 


61.2 


128. 


64. 


16.6 


8.3 


33.2 


16.6 


49.8 


24.9 


66.4 


33.2 


83. 


41.6 


99.6 


49.8 


132.8 


66.4 


166. 


83. 



Fig. 206466. Wrought Iron. 



A'Sq. 


.23 


.13 


.46 


.26 


.69 


.39 


.72 


.62 


1.15 


.65 


1.38 


.78 


1.8 


1.6 


2.3 


1.3 


'Sq. 


.96 


.63 


1.9 


1.1 


2.9 


1.6 


3.8 


2.1 


4. 


2.7 


6.7 


32 


7.6 


4.2 


9.6 


5.3 


A'Sq. 


2.2 


1.2 


4.3 


2.4 


6.5 


3.6 


8.5 


4.8 


10.8 


6. 


12.9 


7.2 


17.3 


9.6 


21.6 


12. 


•s3. 


3.8 


2.1 


7.6 


4.3 


11.4 


6.4 


16.2 


8.5 


19. 


10.6 


22.8 


12. 


30. 


17. 


38. 


2». 


ii'Sq. 


6. 


3.3 


12. 


6.6 


18. 


10. 


24. 


13.3 


30. 


16.6 


36. 


19.9 


48. 


26 6 


60. 


33. 


•Sq. 


8.6 


4. 


17.2 


9.6 


25.8 


14.3 


34.4 


19.1 


43. 


23.9 


61.6 


28.6 


68.8 


38.2 


86. 


47.8 


/■'Sq. 


11.7 


6.5 


23.4 


13. 


35.1 


19.5 


46.8 


26. 


58.6 


32.6 


70.2 


39. 


93.6 


62. 


117. 


66. 


•s<^. 


16.3 


8.5 


30.6 


17. 


46.9 


24.6 


61.2 


34. 


76.5 


42.5 


91.8 


61. 


122.4 


68. 


153. 


86. 



Fig. 2054CC. Soft Steel. 



A'Sq. 


.17 


.12 


.34 


.24 


.64 


.36 


.68 


.48 


.86 


.60 


, 


.72 


1.3 


.96 


1.7 


1.2 


Y'SH- 


.69 


.49 


1.3 


.98 


1.9 


1.4 


2.7 


1.9 


3.4 


2.4 


4.1 


29 


6.6 


3.9 


6.9 


4.9 


h"^- 


1.5 


1.1 


3.2 


.2 


4.6 


3.3 


6. 


4.4 


7.6 


6.6 


9. 


6.6 


12. 


8.8 


16. 


11. 


'Sq. 


2.6 


1.9 


5.23 


.8 


7.8 


6.7 


10.4 


7.6 


13. 


9.6 


15.6 


11.4 


20.8 


16.2 


26. 


19. 


A'Sq. 


4.2 


3. 


8.4 


6. 


12.6 


9. 


16.8 


12. 


21. 


16. 


26.2 


18. 


33.6 


24. 


42. 


30. 


'S<^. 


6.2 


4.4 


12.4 


8.8 


18.6 


13.2 


24.8 


17.6 


31. 


22. 


37.2 


26.4 


49.6 


36.2 


62. 


44. 


/•"Sq. 


8.4 


6. 


16.K 


12. 


25.2 


18. 


33.6 


24. 


42. 


30. 


60.4 


36. 


67.2 


48. 


84. 


60. 


i'Sq. 


iO.9 


7.8 


21.8 


16.6 


32.7 


23.4 


43.6 


31.2 


64.5 


39. 


66.4 


46.8 


87.2 


62.4 


109. 


78. 



Fig. 205Add. Cast Iron. 

2055. Horse-powers of the Motor Equipments for Various 
Machine Tools. The data from which the curves on this chart 
(Fig. 2055) were derived have been gathered from numerous 
sources and actual installations that have been found satisfactory. 
The values plotted are ample for the heavy cuts of general prac- 
tice, and are slightly higher than those given by Mr. Pomeroy — 
General Electric Review, 1908. The several charts which he 



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478 ENGINEERING AND SHOP PRACTICE 



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MOTOR DRIVES AND MOTOR-DRIVEN MACHINE TOOLS 479 

submits, contain the plottings collected from a wide range of 
installations in railroad shops. The diagram is simple and re- 
quires no explanation. However, if it is desired to know the size 
of motor required for a ^2" boring mill, follow the curve marked 
lathes and boring mills to its intersection with the ordinate 
marked 52; follow the abscissa horizontally to the left and read 
the horse-power required, 15. The results obtained by this chart 
are, of course, general; motors are not built in sizes varying by \ 
horse-power or even 3 horse-power and so the commercial motor 
nearest the size obtained is the one to select for ordinary work. 
It should be noted that when heavy chips with high-speed steel 
are contemplated that the horse-power of the motor should be 
governed by the power necessary to remove the chip desired. 
Data for these calculations will be found in Sec. 2054, entitled 
''Horse-power Required to Remove Chips of a Given Area." 



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INDEX 



Abrasive operations, hand, 270. 

procesaes, see grinding. 

wheels, 276 to 284. 

wlieels and speeds, 277. 
Abrasives, alundum, 276. 

carborundum, 276. 

choice of wheel grades and num- 
bers. 281. 

corunaum, 277. 

emery, 277. 

grade of hardness, 279. 

grindstones, 277. 

number of grains, 279. 

scale of hardness, 276. 

surfaces cut by, 279. 
Accumulator, hydraulic, 425. 
Acidity test for oils, 55. 
Acme standard 29** screw thread, 217. 

thread, table of parts, 218. 
Addendum, gear tooth parts, 330. 
Adiabatic compression, 425. 
Adjustable service for motors, 465. 

speed motors, 460. 
Admiralty metal, 45. 
Advantages of motor driving, 453. 
Air compressed, 425. 

compressed, engines, 424. 

for cleaning, 368. 
machines, 424. 

compressors, 424. 

engine, hot, 393. 

hardening steel, 31. 

tempering in, 365. 
Ajax metal, 48. 
Aligning the tap, 164. 
Allowances for reamed holes, 130. 

close running fits, 187. 

driving fits, 187. 

forcing fits, 187. 

free running fits, 187. 

limits for limit gages, 187. 

shrinking fits, 187. 

tapped holes, 148, 153, 154, 155. 
Alloys, aluminum bronze, 47. 

antimony in, 44, 46, 47, 48. 

bearing metals, 47. 

bismutli in, 47, 48. 

bronze, 46. 

bronzes and brasses, 42. 

composition of 24 bearing metal, 47 
26 commercial, 44. 

copper-tin, 43. 



Alloys, copper-tln-sinc, 43 

coppex^zinc, 43. 

fusible, 48. 

German silver, 47. 

Gurley's bronze, 47. 

lead, use in, 44. 

manganese bronze, 47. 

pewter and type metal, 48. 

phosphor bronze, 43. 

properties and characteristics, 42. 

silicon and steel, 31. 

solders, etc., 46. 

steel, 28. 

high-speed cutting, 34. 

strength of, wire. 46. 

telephone and telegraph wire, 46. 

variation of strength, 43. 

white metal, 48. 
Alternating current motors, 420. 

current, systems of distribution, 
418. 

current transmission, 416. 
Alimunum, alloys, 47. 

bronze, 47. 

influence of, 18. 

steel, 33. 
Alundum, 276. 
American ga^, 121, 122. 

twist dnll gage, 121. 

screw gage, 122. 
Ampere, 404. 
Analogies between flow of water and 

electricity, 404. 
Anal>'sis of alloys, see alloys. 

of cast iron, 21. 

of gases, see gases. 

of oils, see oils. 

of steel, see steel. 
Angle belts, 446. 
Angles and bevels, 295. 

and tapers, table of, 116. 

of cuttmg tools, 34, 61, 62. 

tools (see cutting tools). 

of geometrical figures, 116. 

of planing tools, 102. 

of slotter tools, 102. 
Angular milling cutters, 341. 
Ammal oils, 54. 
Annealed castings, 22. 
Annealing castings, 22. 

dry, 365. 

furnace, 11. 

malleable cast iron, 21. 

ordinary, 365. 

physical effect of, 22. 



481 



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482 



INDEX 



Annealing, self-hardening steel, 31. 

water, 366. 
Anti-friction metal, 48. 
Antimony in alloys, 44, 48. 

in bearing metals, 47, 48. 
Arbors or mandrels, 127. 

expanding, 129. 

milling machine, 337. 

presses, 346. 

screw, 337. 

shell mill, 337. 

reamer, 130. 
Armatures, 412. 

circuits, 414. 

disc, 412. 

drum, 412. 

ring, 412. 
Armor plate steel. 28, 29. 
A. S. M. E. Standard Machine Screws, 

155. 
Assembling cutters, collets and collars, 
311, 337. 

presses, 346. 
Arsenic in alloys, 44. 
Axle lathe, 19(3. 



B 



Babbitt metal, 47. 

Back gear speed ranges, 460. 

Backlash in screw cutting, 211. 

Bands or belts, nee belts. 

Bars, boring, 231. 

Basic iron, 21. 

Baths, lead and sand, 366. 

quenching, 365. 
Bearing metal alloys, 47. 

metal, anti-friction, 48. 
Babbitt, 47. 

metals, composition of, 48. 
Bearings and hangers, 439. 

alloys for, 45. 

oil for cleaning, 56. 

overheate<l, 5. 

surface of, 50. 
Beau <le Rochas' conclusions, 386. 
Beauxitc, 276. 
Bell metal, 46. 
Pielting and belts, 447. 

cotton, 447. 

leather, horse-power transmitted 
by, 451. 

rawhide, 447. 

rubber, 447. 

rules for horse-power, 452. 

and belting, 447. 

angle, 446. 

care of, 448. 

centrifugal ten.sion of, 451. 

endless, 448. 

horse-power transmitted by, 451. 

lacing, 448. 

cpiartertwist, 446. 

speed of, 451. 

width of, 451. 
Bench or precision lathe, 100. 



Bench and vise work. Chapter VII, 161. 
Bessemer cast iron, 21. 
furnace, 13. 
iron. 20. 
steel, 26, 35. 
Bevel gears, cutting, 323. 

protractor, 114. 
Bevels, planing, 295. 
Birmingnam or Stub's wire gage, 121. 

gage, 122. 
Bismuth in alloys, 44. 

in fusible allo>^, 48. 
Blacking iron and steel, 367. 
Blast furnace, 12. 
Bluing iron and steel, 366. 
Bolt and thread data, U. S. Standard, 

148. 
Bolta, carriage, 144. 
coupling, 143. 
machine, 142. 
stove, 146. 
strength of, 148. 
stud, 145. 
Bores, counter, 233. 
Boring, Chapter IX, 220. 
bars and cutters, 231. 
or chucking drills, 234. 
defined, 220. 
and facing, milling, 316. 
machine, liorizontal, 220. 

the lathe as a, 222. 
vertical, 221. 
machines, power re<|uired for, 478. 
mills, characteristic o( erations, 224. 
description of ]^art«, 223. 
function and limitations, 223. 
operations, adjustment on face 

plate, 227. 
operations, adjustment on carriage, 

227. 
operations, chucking, 226. 

lathe, 225. 
order of operations for lathe, 227. 

for mill, 227. 
preparation of the work, 225. 
tool, 98. 

and turning mills, motor driven, 
222. 
Box tools and turners, 351. 

tools, illustrations of, 352 to 358. 
BraKs, see alloys, 
bearings, 45. 
copper-zinc alloys, 43. 
malleable, 46. 
naval, 45. 
Tvd, 46. 

tough for engines, 46. 
working tools, 99. 
yellow, 45. 
BraRHos, comi)osition of commercial, 44. 
Brazing, 368. 

cast iron, 369. 
metal, 45. 
sohler, 45. 
Breast water wheel, 396. 
Briggs' standard pipe thread, 138. 
Brine, quenching bath, o65. 



Digitized by 



Google 



INDEX 



483 



British standard imperial wire gage, 
122. 

standard or Whitworth thread, 
218. 
Broaching or drifting, 175. 

tools, 176. 
Bronze, see alloys. 

aluminum, 47. 

carbon, 48. 

composition of commcrical, 44. 

Cornish, 48. 

Damascus, 48. 

for eccentric straps, 46. 

Graney, 48. 

Gurley's, 47. 

Harrington, 48. 

manganese, 47, 48. 

phosphor, 43, 46, 48. 

for pieces subject to shock, 46. 

for pump casings, 46. 

for rod boxes, 46. 

silicon, 46. 

Tobin, 45, 48. 

for whistles, 46. 
Bronzes, copper-tin alloys, 43. 
Brown it Sharpe or American gage, 121 
gage, 122. 
tapers, 2(K5. 
29** wonn thread, 217. 
British thermal unit, 371, 395. 

units in jwwer gases, 395. 
Buffing, 270. 
Bull ntjse tool, 98. 

Bullock system of speed control, 467. 
Burrs, 145. 
Bush metal, 45. 



Cadmium, 49. 

Calcining or roasting furnace, 12. 

Caliper gages, 118. 

micrometer, square, 109. 
Calipers, 130. 

henna{}h rodi te, 131. 

in.side, 131. 

micrometer, 106. 

outside, 131. 

a pa^e of, 132. 

Vernier, 112. 
Caloric engine, 393. 
Calorific power of gases, 392, 395. 
Capacity, unit of, 404. 
Cape chisel, 93. 
Cap screw, 140. 

.standard tabulatcxl data, 153. 
Carbon, bronze, 48. 

cement ite, 36. 

content, effect of, 19. 

influence of, 14. 

pearlite, 36. 

or tool steel, 27. 
Carbonizing iron, 23. 
Carborundum, 276. 
Card file, 168. 
Carefulness in the shop, 3. 



Care of chucks, 231. 
files, 168. 
machines, 4. 
milling cutters, 340. 
self, 4. 
Carmelia metal, 48. 
Carriage, adjustment on, 221. 
bolts, 144. 
lathe, 196. 
Car wheel iron, 21. 
Case-hardened castings, 23. 
Case-hardening and other processes, 
366. 
hardening solutions, 23. 
Castings, see cast iron, 
annealed, 22. 
brazing, 369. 
ca.se-hardened, 23. 
case-hardening, 366. 
cleaning with air, 368. 
pickling, 367. 

removing grease and dirt, 367. 
steel, 35. 
Cast iron, see castings. 
Cast iron, 13. 

analyses of standard, 21. 
Bessemer, 21. 
brazing, 369. 
car wheel, 21. 
ca.se-hardening, 366. 
chemical elements in, 21. 
chill roll, 21. 
clas.sification, 21. 
comparison with wrought iron, 

and steel, 23. 
general machincrj', 21. 
gun metal, 21. 
malleable, 21. 
physical proj)erties of, 18. 
power re<iuiretl for cutting, 

476. 
specifications for, 21. 
stove i)late, 21. 
Cementite, hardening carbon, 36. 
Center gage, method of using, 124. 

punches, 131. 
Centering, 201. 

Centrifugal tension of belts, 451. 
Change gearing, 208. 
Characteristic o|)erations, boring mill, 
224. 
o|ierations, drilling machines, 245. 
engine lathe, 199. 
planer, 292. 
shaper, 288. 
turning mill, 224. 
universal grinder, 269. 
universal miller, 308. 
Characteristics an<l design of jigs, 364. 
of a drill, 246. 
of files, 170. 
Charcoal iron, manufacture of, 24. 

pig iron, 20. 
Chattering, grrinding, 273. 

in machme scraping, 173. 
of tool, 79. 
Check system for tool rooms, 7. 



Digitized by 



Google 



484 



INDEX 



Chemical browns and blacks, 367. 

properties of oils, 67. 
Cliill roll iron, 21. 
Cliipping and its applications, 165. 

the chisel, 166. 

the cut, 166. 

grooves, 168. 

pneumatic hammers, 165. 

a wide surface, 167. 

the work, 166. 
Chips, horse-power required to remove, 
472. 

power required, Campbell's for- 
mula, 471. 

pressure of, on tools, 75. 
Chisels, 93, 166. 

cape, 93. 

cold, 93. 

round nose, 94. 
Choice of an electric motor, 465. 
Chrome nickel steel, 29. 

steel, 28. 

vanadium steel, 32. 
Chromium, influence of, 16. 
Chucking, atljustments in chucks, 226. 

boring bars and cutters, 231. 

counter bores, 233. 

drills, 233. 

on face plates, 227. . 

on carriage, 227. 

reamers, 233. 

tools, 231. 
Chucks, adjustment in, 226. 

and chucking tools, 228. 

automatic, 351. 

care of, 231. 

combination, 230. 

drill, heavy, 256. 

drill, light, 254. 

geared scroll, universal, 229. 

independent, 229. 

spur-geared, scroll combination, 
231. 

tapping, 256. 

universal. 229. 
Circuits, divicled, 406. 

electric, 406. 

for motors, 469. 

grounded, 406. 

parallel, 406. 

series, 406. 
Circular pitch, 328. 

pitch table, 330. 
Cleaning ca.sting8 and forgings, 367. 
Clearance angle of cutting tools, 61. 

and lip angles of tooLs, 72. 
autches, 442. 

compression, 441. 

friction, 440. 
Coach screws, 142. 
Coal con8umf)tion, 385. 
Cobalt, influence of, 18. 

steel, 33. 
Coeflicient of expansion, iron and steel, 
20. 

of friction, 51. 
Cold chisel, 93. 



Cold sawing, 163. 

test for oil, 55. 
Collars, etc., assembling, 311. 
Collets and cutters, assembling, 311. 

drill. 254. 

milling, 338. 
Coloring, iHacking iron and steel, 367. 

blum^ iron and steel, 366. 

chemical blacks, iron and steel, 367. 

chemical browns, iron and steel, 
367. 

iron and steel, preparatory pro- 
cesses, 366. 
Combination chucks, 230. 
Commutators, 411. 
Composition of allovs, 44. 

of gases, B. T. U., 394, 395. 
Compound engines, 385. 

gearing, 210. 

motors, 463. 

service for motors, 465. 

wound dynamos, 414. 
Compressed air for cleaning castings, 
368. 

air blast for cupulas, 425. 
engines, 424. 
machines, 424. 
for mining operations, 424. 
for pneumatic service, 425. 
transmis.sion, 423. 
Compression, adiabatic, 424. 

clutches, 442. 

isothermal, 424. 
Compressors, air, 424. 
Conauctivity, electrical, of iron and 
steel, 20. 

relative of wire, 46. 
Conical grinding, 271 . 

grinding, order of operations, 275. 
Conservation of energy, 371. 
Constant current transmissions, see con- 
tinous. 

speed motors, 458. 

speed service for motors, 465. 
Consumption, comparative coal and 

steam, 385. 
Continuous current transmission, 416. 
Control, speed, of electric motors, 467. 

speed, relations, 468. 

systems and wiring, 468. 
Copper alloys, see alloys. 

-tin alloys, 43. 

-wire, 46. 

-zinc alloys, 43. 

-zinc-tin allo>^, 43. 
Cordage, see rope. 
Cornish bronze, 48. 
Corundum, 277. 
Cost of motor equipment, 453. 
Cotters, 145. 
Cotton belting, 447. 

mills, rope drive, 420. 

rope transmission, 431. 
Coulomb, 404. 
Counterbores, chucking, 233. 

bores, combination, 235^ 

boring, 237. 



Digitized by 



Google 



INDEX 



485 



Counterbores, shafting, 437. 

sink and drill combined, 252. 

sinking, 237. 

sinking bit stocks, 251. 
and drilling, 201. 
Ck>upling bolts, 143. 
Couplings, 442. 

compression, 442. 

flange, 442. 

jaw, 443. 

plate, 442. 

sleeve, 442. 

universal, 443. 
Crank-shaft lathe, 100. 
Cross filing, 169. 
Crowning, pulley, 444. 
Crucible cast steel, 26. 
Current, alternating, motors, 420. 

continuous, 416, 417. 

direct, 416, 417. 
Curtis turbine, 381. 

turbine nozzles and buckets, 381. 
Cuts, chipping, 167. 

dry, 60. 

horse-power requirements for, 472. 

of files, 170. 

planing under cuts, 295. 

planing, terminating in a shoulder, 
295. 

roughing and finishing, 294. 

side and down, 294. 
Cutter diameters, 310. 

grinder, universal, 261. 
Cutters, see mills. 

angular milling, 341. 

boring bar, 231. 

care of milling, 340. 

classification of milling, 338. 

collets and collars, assembling, 311 

cutting action of, 312. 

design of milling, 338. 

end milling, 342. 

face milling, 340. 

fly milling, 342. 

form millm^, 342. 

formed milhng, 342. 

gang milling, 345. 

inserted tooth, 342. 

key way, 290. 

nicked tooth, 340. 

a page of, 339. 

screw slotters, 344. 

side milling, 341. 

slitting saws, 344. 

spiral, milling a, 325. 

straddle, 345. 
Cutting action of mills, 312. 

bevel and miter gears, 323. 

cast iron, horse-power required, 
476. 

ear, 316. 

ard steel, horse-power required, 
473. 

key ways, 174. 

metals, art of, 34. 

oflF tool, 97. 

oils, 58. 



gea 
hap 



Cutting and sizing gear wheels, 327. 
soft steel, ho roe-power required, 

475. 
speeds for drills, 247. 
for files, 205. 
for grinding, 272. 
for planer, 294. 
speeds, revolutions for, 88. 
tool steel alloys, 34. 

steel, 72. 
tools, chapter IV, 61. 
angles of, 34. 
angles of lip and clearance, 

chatter of, 79. 
cooling the tool, 78. 
cutting force and area, 84. 
depth of cut and feed on 

speed, 81. 
durability of, 61, 83. 
forging and grinding, 73, 81. 
governing conditions, 61. 
keenness of, 61. 
lathe, 97. 
life of, 80. 
planer, 100. 
pressure of chip, 75. 
quality of metal being cut, 

82. 
recent practice with high 

speed steels, 89. 
relative positions of tools 

and work, 61. 
shape of material to be cut, 

62. 
slide rules, 82. 
Blotter, 102. 

speeds for cast irons, 87. 
speed and texture, 84. 
strength and durability of 

edge, 61. 
wrought iron, horse-power 
rc<]uired, 474. 
Cycle, clerk, 387. 
four, 387. 
Otto, 387. 
two, 387. 
Cydoidai engine, 385. 
system. Grant's, 331. 
teeth, table of, 332. 
Cylinder oils, 57. 

Cylindrical gages, standard, 118. 
grinding, 271. 

grinding, order of operations, 275. 
work, laying out, 161. 



D 



"D" drill, 249. 
Damascus steel, 32. 

bronze^ 48. 
Decarburizmg furnace, 13.^ 
Decimal equivalents of an inch, 152. 

equivalents of various gages, 122. 
Degras (wool fat), 54. 
DeLaval turbine, 379. 



Digitized by 



Google 



486 



INDEX 



DeLaval turbine nozzles and buckets, 

379. 
Delta metal, 48. 
Density test for oils, 55. 
Depth gage, 126. 
Diagonal filing, 169. 
Diametral pitch, 328. 
Diamond point lathe tool, 97. 

point graver, 94. 

point planer tool, 101. 
Die neadj automatic, 359. 

making, 350. 

presses, 346. 
Dies, adjustable, 137. 

curling, 350. 

drawing, 350. 

embossmg, 350. 

for die presses, 350. 

forming, 350. 

machine or solid bolt, 137. 

screw plates, 137. 

and taps, standard X)ipe, 138. 
Diesel engine, 390. 
Dimensional gages, 117. 
Direct current, see current. 
Disc grinder, 258. 

Distribution, electrical systems of, 417. 
Dividers, 131. 
Dividing head drum, 308. 

head, universal, 306. 

in the lathe, 369. 

milling operations, 306. 
Dowel and taper pins, 147. 
Dow turbine, 378. 
T>raw filing, 169. 
Drawing, die, 35f). 
Drifting or broaching, 175. 
Drift or drill key, 254, 255. 
Drill, characteristics of a, 246. 

and countersink combined, 252. 

chucking, 233. 

chucks, neavv, 256. 
light; 254. 
tapping, 256. 

cutting speeds, 246. 

''D,"249. 

flat, 234, 248, 251. 

gage, American twist, 121. 

grinder, 262. 

half round, 249. 

hog nose, 234, 249. 

keys or drifts, 254, 255. 

lands, backing off, 327. 

methods of relieving, 251. 

lipped, 248. 

modified hog nose, 249. 

motor driven, 240. 

oil groove, 235,251. 

radial, 242. 

scraping edge, 249. 

sensitive friction, 238. 

shanks, 252. 

Morse taper, 253. 

sleeve, 254. 

sockets and collets, 254. 

sj)eeds, 246. 

straight fluted, 250. 



Drill, tapping attachment for, 239. 

twist, 250. 

left hand, 251. 

universal, 242. 

upright, 239. 

work, laying out, 162. 
Drills, chucking, 234, 249. 

oil tube, 235. 

and reamers, 235, 251. 

relieving, 327. 

special, and countersinks, 251. 
Drilling, allowances for reamed holes, 
130. 

allowances for tapped holes, 148. 

chapter X, 237. 

characteristic of^erations, 244. 

and countersinking, 201. 

depth of tapped holes, 165. 

drawing the drill, 245. 

feeds and speeds, 92, 246. 

iigs, 363. 

laying out, 244. 

machines, 237. 

machines, power required for, 478. 

operations, 237. 

order of oi)erations, 245. 

preparation of work, 244. 

speeds, 246. 
Drive, roi)e, 430, 431. 
Driver for face-plate work, 226. 
Drives, motor, advantages of, 453. 

motor, cost of etjuipment, 453. 
economy of, 455. 
retjuiring compound ser- 
vice, 465. 

rope, 426. 

rope, continuous 8y.stem, 428. 
for cotton mill, 426. 
multiple svstem, 427. 
systems of, 427. 
Driving fit allowances, 187. 

fits, 183. 

machine tools, motors for, 468. 

rope, 426. 

systems of rope, 427. 
Ductility and cartxjn content, 19. 

of iron and steel, 13, 20, 25. 
Dynamo armatures, 412. 

commutators, 411. 

descrii)tion of, 409. 

field magnets, 413. 

see generator. 

princij)les of, 410. 

windings, 413. 
Dyne, 403. 
Dry annealing, 365. 

cuts, 60. 

grinder, 258. 



Economy of electrical transmission, 417. 

of good lubricants, 53. 

of motor tlrives, 455. 
Kfficiency of Diesel engine, 392. 

of dynamos and generators^ 414. 



Digitized by 



Google 



INDEX 



487 



Efficiency of electric sjrstems, 415. 
of electric transmission, 416. 
of engines and turbines, 385. 
of fuels, 392, 394, 396. 
of eas' engines, 388. 
of liydraulic apparatus, 426. 
of motor drives, 455. 
of motors and generators, 414. 
of water-wheels, 396. 
Ela.stic limit of steel, sec steel. 
Elasticity^ modulus of, 20. 
Electric circuits, 406. 

distribution, syst4?m8 of, 417. 
driving, advantages of, 453. 
d>'iiamoB, 409. 
generator, 409. 
motors, 418 to 423. 
systems, efficiency of, 415. 
transmission, 415. 

efficiency of, 415. 
governing conditions, 

415. 
long distance, 415. 
methods of, 416. 
selection of systems, 

415. 
systems, 417. 
tabulated data, 17. 
Electrical conductivity of iron and steel, 
20. 
conductivity of wire, 46. 
machines, ace generators and mo- 
tors, 
resistance of manganese stoel, 31. 
standards of mea.su rements, 403. 
svmbols, 403. 
units, 403. 
Electricity, analogv between the flow 
of water and, 404. 
elementary, chapter XVIII, 403. 
induction and magnetism, 407. 
standards, laws and facts, 403. 
Electro-magnets, strength of, 408. 

magnets, traction of, 408. 
Elementary electricity, chapter XVIII, 

403. 
Embossing, die making, 350. 
Emery, 277. 

selection of wheel grades and num- 
bers, 281. 
wheels antl speeds, 277. 
End milling cutters, 342. 
slots, 311. 
mills, cutting action of, 312. 
Energy, kinetic 371, 403. 

kinetic ana potential, 403. 
Engine, caloric, 393. 
comj)ound, 385. 
compressed air, 424. 
Diesel, 390. 
exj)erimeiit in thcrmo-dynamics, 

372. 
fuels, gas, 392, 394, 395. 
gasoline, 393. 
gas, operation, 393. 
hot air, 393. 
indicator card, 373. 



Engine lathe, characteristic operations, 
199. 

lathes, description, 190. 

naphtha, 393. 

oils, 57. 

piston-valve, 377. 

power and steam computations, 
374. 

section of vertical, 377. 

steam, 376. 

table of comparative steam and 
coal consumption, 385. 
Equipment, cost of motor drive, 453. 

norse-f)ower for machine tools, 477. 

shop or laboratory, 6. 
Erg, 403. 

Errors, accuracy and, planing, 295. 
Expanding arbors, 129. 

mandrels, 129. 
Expansion, iron and steel, 20. 



Face milling, 314. 

milling cutters, 340. 

action of, 312. 

plate, adju.stment on, 227. 
Facing and boring, milling, 316. 

sjwt, 316. 
Facts, electrical, 403. 
Faggot iron, manufacture of, 24. 
Farad, 404. 
Feather keys, 173. 
Feeds and speeds, 62. 

author's investigations, 64. 

character of chij), 62. 

drilling, 92. 

general rules, 63. 

{rrinding, 272. 
ligh speed tool steels 72, 82. 

low sjieed tool steels, 64. 

milling, 90, 311. 

Nicholson's Investigations, 70. 

planing, 93, 294. 

recent practice with high 8[)eed 
steels, 89. 

revolutions for given diameters, 88. 

surfaces of metals, 62. 

Taylor's investigations, 72. 

turning, 89. 

weight of metal removed at, 477. 
Ferro-fixing, 369. 

manganese steel, 30. 

silicon iron, 21. 
Field ma^iets, 413. 

rotating, induction motors, 422. 
File, *• float," 177, 204. 

table, shapes, cuts and uses, 171. 
Files, care of, 168. 

and their characteristics, 170. 

cutting speeds for, 205. 
Filing, cross, 169. 

diagonal, 169. 

draw, 169. 

iigs, 363. 

lathe work, 204. 



Digitized by 



Google 



488 



INDEX 



Filing and files, 168. 

application and practice, . 
168. 

the tools, 168. 
Finishing processes, lathe work, 204. 

segment and spot, milling, 316,321. 

tool, lathe, 99. 
Fire test for oil, 55. 
Fits, driving, 183. 

and fittmg, 176. 

investigation, 176. 
limits for limit gages, 

185. 
tabulated data relative 
to, 187. 

forcing, 177. 

pressures for forcing, 179. 

running, 184. 

shrinking, 182. 
Fitting, investigation, 176. 

key, 173. 

processes, 176. 
Flash test for oils, 55. 
Flat drill, 234, 248, 251. 
Fluid friction, 52. 
fluting and key seating, 316. 
Fly cutters, 342. 
Force, 403. 
Forcing fits, 177. 

fits, pressure, 179. 

tabulated data, 187. 
Foreword, 1. 
Forging cutting tools, 36, 40, 42, 73, 81. 

hj'draulic, 425. 

square holes, 369. 
Forgings. cleaning castings and, 367. 
Form milling cutters, 342. 
Formed cutters, 342. 
Fonning die, 350. 

lathe, 361. 

lathe work, 363. 
Foundr>' iron, 20. 
Friction, 50. 

clutches, 440. 

coefficient of, 51. 

drill, sensitive, 238. 

fluid, 52. 

laws of, 51. 

lubricant, 59. 

lubricants and lubrication, chap- 
ter III, 50. 

reduction, 50. 

solid, 52. 
Fuels, gas engine, 392, 394, 395. 
Furnace annealing, 13. 

Bessemer, 12, 13. 

blast, 12. 

calcining, 12. 

decarburizing, 13. 

open hearth, 13. 

puddling, 13. 
Fusible allovs, 48. 

alloys, bismuth in, 44. 

plugs, 49. 



Gage, American, 121, 122. 

Birmingham or 8tub's wire, 121. 

British Imperial standard, 122. 

Brown and Sharpe, 121, 122. 

center, 124. 

depth, 126. 

machine and wood screw, 123. 

Roebling'8, 122. 

screw, American, 122. 

screw pitch, 124. 

Trenton Iron Go's, 122. 

twist drill, 121, 124. 

twist drill and st^el wire, 124. 

universal surface, 126. 

U. 8. standard, 121. 

U. S. standard for sheet and plate 

iron, 121, 122. 
Washburn and Moen's. 121, 122. 
Gages, caliper standard, 118. 
classification, 117. 
cylindrical, 118. 
limit, 119. 
limit.s for limit, 185. 
numbered, criticism of, 120. 
snap, 118. 

test and reference, 117. 
wire, sheet metal and others com- 
pared, 122. 
Gang mills, 345. 
Gap lathe, 189. 
Gas, blast, 394. 
coal, 394. 
coke oven, 394. 
commercial power, 394, 395. 
constituents of power, 395. 
engines. Clerk cycle, 387. 
engine, discussion of details, 386. 
four cycle, 387. 
fuels, 392. 
Koerting, 389. 
methods of regulation, 388. 
oils, 57. 
operation, 393. 
Otto cycle, 387. 
theory and thermo-dy- 

namics, 386. 
two cycle, 387. 
heat value of, 395. 
natural, 394. 
oil, 394. 
oil-water, 394. 

power, constituents of, 395. 
producer, 394. 
water, 394. 
Gasoline engines, see gas engines. 
(Joar cutting, 316. 

bevel and miter, 323. 
bobbing a worm wheel, 322. 
teeth, cycloidal, 331. 
internal, 333. 
involute, 332. 
odontographies, laying out, 

331. 
rack, 333. 
table of cycloidal, 332. 



Digitized by 



Google 



INDEX 



Gear teeth, table of involute, 334. 
tooth parts, 330. 
wheels, siang and cutting, 327. 
Gears, cycloidal. Grant's layout, 33 \. 
8ee gear. 

internal involute, 333. 
involute, Grant's layout, 332. 
notes on, 335. 

plotting Lewis' value of *'s," 336. 
rack, laying out involute, 333. 
rules for calculating, 327. 
sizing and cutting, rules, 327. 
strength, sp>eed, norse-jaower, 335. 
table of tooth parts, 330. 
Gearing, change, 208. 
compound, 210. 
notes on, 335. 
odontographies, laying out gear 

teeth, 331. 
simple, rule, 209. 
Generator, see d3mamo. 
armatures, 412. 
commutators, 411. 
description, 409. 
field magnets, 413. 
principles of, 410. 
turbine set, Curtis, 382. 

DeLaval, 379. 
Westinghouse-Parsons, 
385. 
windings^ 413. 
Geometrical figures, angles of, 116. 
German silver, 47. 
German silver solder, 47. 
Gold solder, 47. 

Grade of abrasive wheels, 279, 281. 
Grain of abrasive wlieels, 279, 281. 

character of surface cut by, 279. 
Graney bronze, 48. 
Graphite bearing metal, 48. 

as a lubricant, 59. 
Graph, advantages individual motor 
drives, 454. 
cooling and heating curves, high 

8i3eed steel, 39. 
cooling and heating curves, ordi- 
nary steel, 38. 
curves for shunt and compound 

motors, 459. 
eflFect of carbon content, 19. 
feeds and speeds, brass and tool 

steel, 67. 
feeds and speeds for cast iron, 68. 
feeds and speeds, for wrought iron 

and machinery steel, 69. 
of forcing, shrinking and driving 

fits, 178. 
gears, Lewis, value of "s," 336. 
horse-power of maniUa ropes, 432. 
horse-power, motor equipment of 

mactiine tools, 478. 
horse-power to remove cast iron 

chips, 476. 
horse-power to remove hard steel 

chips, 473. 
horse-power to remove soft steel 
chips, 475. 



Graph, horse-power to remove wrought 

iron chips, 474. 
indicator card, 374. 
limits for limit gages, 186. 
metallurgy of iron, 12. 
polyphase induction motor, 463. 
power, 374. 
power consumption in motors and 

machines, 456. 
power losses in motors and ma- 
chines, 457. 
pressure factor, forcing fits, 180. 
relations between cutting force and 

area of cuts, 84. 
running fits, 186. 
series wound continuous motor. 

461. 
single phase series A. C. motor, 

461. 
speed -torque curves, induction 

motor, 462. 
variations of cutting speed with 

hardness of cast iron, 86. 
variation, durability of tool with 

cutting speed, cast iron, 85. 
weights of variable speed motors, 

470. 
Gravers, 94. 

diamond point, 04. 
round nose, 95. 
Gravity test for oils, 55. 
Gray iorge iron, 21. 
Greases, 58. 

removing, 367. 
Grinder, cutter, 261. 
disc, 258. 
driU, 262. 

dry and attachments, 258. 
reamer, 261. 
universal, 264. 
universal, controlling mechanism. 

266. 
imiversal cutter and reamer, 261. 
universal, description of parts, 267. 
wet, 260. 
wet drill, 263. 
Grinding, chapter XI, 258. 
buffing, 270. 
chattering, 273. 
cutting tools, 72, 73, 93 to 105. 
cylindrical and conical, 271. 
discussion and classification, 271. 
hand, 270. 
hand surfacing, 270. 
hand tools, 93. 
lapping, 276. 
lathe tools, 97. 

machine abrasive op>erations, 270. 
machines, power reauired for, 478. 
operations, hand ana machine, 258, 

270. 
order of operations, 275. 
planer tooLs, 103. 
preparation of the work, 270. 
remarks and reputable practice, 

274. 
slotter tools, 102. 



Digitized by 



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490 



INDEX 



Grinding, si>oods, traverse and tempera- 
ture, 272. 

trial settings, 273. 
Grindstones, 277. 
Groovesj ehip]iing, 168. 

engineer's standard, 430. 

idler, 429. 

Jones and Laughlin, 430. 

planing, 295. 

standard drive, 429. 

straight side drive, 429. 
Grooving, helical, 325. 

spiral, 319, 325. 
Gun metal, 45. 

hard, 45. 

iron, 21. 

Gurley's bronze, 47. 



H 



Hack sawing, 163. 
Half round drill 234, 249. 
Hammering ancl peening, 162. 
Hammer refining, 36. 
Hammers, machinists, cop|)cr, Ioa<l, 
rawhide, 163. 

pneumatic, 165. 
Hand grinding, 258, 270. 

laUie, 190. 

surfacing^ 270. 

tools, chiHt»ls, 93. 
gravers, 94. 
grinding and use, 93. 
8cra|)ers, 95. 
Hangers and [Hearings, 439. 
Hanger screws, 142. 
Hardening, quenching baths, 365. 

steel, thcH)ry of, 36. 

and tempering, 40. 

and tempering data, 40. 
Harrington bronze, 48. 
Heat cnHsi]>ating lubricants, 60. 
mixtures, 60. 

dissipati<m, cooling the tool, 78. 

experiment in thermodynamics, 
372. 

relation between work and, 371. 

theory of, 371. 

treatment of steel, 35. 

unit, 371. 

value of gaxes, 395. 
Helical or s])iral grooving, 325. 
Hematite, 11. 
Henry, 404. 

High speed cutting steels and alloys, .34. 
stviA, Tungsten, 31. 
Mushet, 31. 
Hobbing a worm whwl, 322. 
Hob, pipe, 138. 
Hog nose drill, 234, 249. 

modified or "D," 249. 
Holes, depth of tapp<»d, 165. 

stjuan*, forging, 369. 
Horst»-j)ower, (-ampbell's fomnila, 471. 

consumption, motor drives, 456. 

of gearing, 335. 



Horse^power losses, 456. 
manilla rope, 431. 
of motor e<{uipment8 for machine 

tools, 478. 
motor ratings, 469. 
required for cutting cast iron. 476. 
hard steel, 473. 
soft steel, 475. 
wrought iron, 
474. 
to remove chips of given 
area, 472. 
requirements, electric, 469. 

of reciprocating tools, 
471. 
of st^am engines, 374. 
transmittal oy leather belting, 451. 
Hot-air engines, 393. 

boxes, see bearings. 
Hydraulic forging, 425. 
impulse wheels, 399. 
motors, 396. 
presses, 346. 
reaction wheels, 399. 
transmission, 425. 

uses, 425. 
turbines, 396. 
turbine, Doble, 399. 
Pelton, 398. 
water-wheels, 396. 



Impulse wheels, 396, 399. 

Inch, decimal equivalents of an, 152. 

Independent chucks, 22^). 

Index drum, universal miller, 308. 

Indicator card, 373. 

Induction and magnetism, 407. 

and magnetism, historical note, 407. 

motors, 422, 460. 
Inserted tooth cutters, 342. 
Inspection, oil, 5(5. 
Instniction, character of, 2. 
Internal ^ears, laying out, 333. 
Introduction and' €?quiprient, chapter 

I, 1. 
Invar, 34. 

Investigation, author's, feeds and 
sneetls, 63, 64. 

NicnoLson's, feeds and speeds, 70. 

Taylor's, feeds and sjjeetls, 72. 
Involute internal gears, laying out, 333. 

rack, laving out, 333. 

svstem, 'Grant's, 332. 

t<>eth, table of, 334. 
Iron, basic, 21. 

Bessemer, 20. 

carb<m content, 19. 

case hardening, 366. 

cast, 13, 21. 

cast, |)ower required for cutting, 
476. 

charcoal, 20. 

coloring, 366. 

conductivity of steel and, 20. 



Digitized by 



Google 



INDEX 



491 



Iron, ferro-silicon, 21. 

foundry, 20. 

gray forge, 21. 

metallui^gy of, 11. 

other processes of working, 366. 

physical properties of cast, wrought 
and steel, 18. 

pure, 13. 

pure, chemical composition, 24. 

and steel, working, 365. 

wrought, power required for cut- 
ting, 474. 
Isothermal compression, 424. 



Jigs, characteristics of, 364. 

design of, 364. 

drilling, 363. 

filing, 363. 

templets, 364. 
Joint, rust, 369. 
Joule 371, 404. 
Joule's equivalent, 371. 
Journal, see bearings. 



K 

Keenness, angles of, 61. 

of tool, 61. 
Key, drift or center, 255. 

feather, 173. 

fitting, 173. 

nomenclature, 173. 

seating, milling, 316. 

seats, table of standard, 175. 

Woodruff patent, 173. 
Key-way cutters, 290. 

way cutting, 174. 
Kinetic energy, 371. 
Kinks, divitung in the lathe, 369. 

forging square holes, 369. 

miscellaneous, 369. 

rust joint, 369. 



Lacing, bolt, 449, 450. 
Lag screws, 142. 
Lapping, 376. 
Lathe, apron front, 198. 

apron mechanism, back, 198. 

axle, 190. 

bench or precision, HM), 193. 

as a boring macliine, 222. 

boring operations, 225. 

crank-shaft, 190, 192. 

dividing in the, 369. 

engine, characteri.stic operations, 
199. 

engine, description, 190. 

forming, 301. 

gap, 189. 

monitor, 360. 



Lathe, motor driven, 197. 

order of boring oi)erations, 227. 

patent liead, 188. 

pulley, 190, 192. 

scraping in the, 173. 

scK^tion through hea<I -stock, 198. 

speed or hand, 190, 193. 

ta()er-tuming attachment, 199. 

tool-holders, 103. 

tool-maker's, 188. 

tools, 97. 

boring, 98. 
brass-working, 99. 
bull-nose, 98. 
diamond-point, 97. 
finishing, 99. 

parting or cutting-oflF, 97. 
round-nose roughing, 97. 
with self-hardening steel cut- 
ters, 103. 
side, 97. 
threading, 98. 
turret, HK), 350. 
wheel, 190. 
Lathes, 188. 

horse-power of motor equiiunent, 
478. 
Laws of ele<*tricity, 404. 
of friction, 51. 
magnetic, 407. 
Laying out bevel and miter gears, 323. 
centering, 201. 
chipping work, 166. 
cylmdrical work, 161. 
for drilling, 244. 
drill work, 162. 
pear teeth, 331. 
internal involute gears, 333. 
involute rack, 333. 
preliminary proces.ses, 161. 
rectiUnear work, 161. 
Lead of screws, 135, 214. 
Lead, antimonial, 48. 
bath, Sm. 
hard, 48. 
use in alloys, 44. 
Leather belting, 447. 

belting, horse-jxiwer transmitted 
by, 451. 
Limit gages, 119. 

adjustable, 120. 

limit.s for, 185. 

limits for, tabulated data, 

187. 
stamlard, 119. 
Limonite, 11. 

Liners or shims for broaching, 176. 
Lipped drill, 248. 
Lubricant application, 59. 
friction, 59. 
mixtures, 60. 
Lubricants, chemical and phy.sical prop- 
erties of 12 ordinary lubricating 
oils, 57. 
economy of, 53. 
function of, 53. 
graphite, 59. 



Digitized by 



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492 



INDEX 



Lubricants, heat dissipating, 60. 

linseed oil for assembling fits, 178. 

qualifications of a good, 54. 

for scraping, turpentine, 173. 

selection of| 53. 

talc, 60. 

use of solid, 59. 
Lubricating oils, qualifications of, 54. 

oils, see oils. 
Lubrication, chapter III, 50. 



Machine bolts, 142. 

boring, horisontal, 220. 
vertical, 221. 

and hand {[grinding, 258, 270. 

milling, honzontal, 298. 

ordinary type, 298. 
plain, 298. 
universal, 302. 
vertical, 298. 

oils, 57. 

planing, key-way cutters, 290. 

screw proportions and other data, 
old style standard, 154. 

screw taps, 136. 

screw, tap and thread data, A.S. 
M.E. standard, 150. 

screw, tap and thread data, old 
style, 149. 

screws, 138. 

screws, A.S.M.E. standard pro- 
portions, and data, 155. 

screws, flat fillister head, A.S.M.E. 
standard, 159. 

screws, flat head, A.S.M.E. stand- 
ard, 157. 

screws, oval fillister head, A.S.M.E. 
standard, 160. 

screws, round head, A.S.M.E. 
standard, 158. 

screws, special, A.S.M.E. stand- 
ard, 156. 

tool eauipment for school shof s, 6. 

tools, norse-power of motor equip- 
ments for, 478. 

tools, motors for, 458, 478. 

universal grinding, 264. 

and wooti screw gages, 123. 
Machines, boring, 220. 

care of, 4. 

compressed air, 424. 

drilling, 237. 

grinding, 258. 

milling, 298. 

planing, 285. 

planing, classes of, 285. 

screw, 359. 

turning, 188. 

turret, 350. 
Machinery iron, analyses of, 21. 

oils, 57. 
Magnetic circuits, 407. 

field, strength of, 407. 

non-, steel, 30. 



Magnetism and induction, 407. 

and induction, historical note, 407. 
Magnetite, 11. 
Magnet, etectro-,traction of, 408. 

field, 413. 
Magnets and magnetic laws, 407. 

and solenoids, strength of, 408. 
Magnolia metal, 48. 
Malleable brass, 46. 

cast iron, 21. 
Mandrels, see arbors. 

expanding, 129. 
Manganese bronze, 47, 48. 

influence of, 15. 

steel, 30. 
Manipulation and processes, screw cut- 
ting, 211. 

straight turning, 202. 
Marine and wet ser\nce oils, 58. 
Materials, chapter 11. 11. 
Measurements, stanaard of, 105. 
Measuring and small tools, chapter V, 

tools, 105. 

bevel protractor, 114. 
gages, 117. 

micrometer calipers, 106. 
micrometer caliper square, 

109. 
rules, 105. 
straight edge, 113. 
try sjquare, 106. 
vernier. 111. 
vernier calipers, 112. 
Mechanics, chapter XVI, 370. 

fundamental principles, 371. 
Mercury, quenching bath, 365. 
Metal, admiralty, 45. 

alloys, composition of 24 bearing, 

47. 
Ajax, 48. 
American, 48. 
anti-friction, 48. 
Babbitt, 47. 
bearing, 47. 
bell, 45. 
brazing, 45. 
bush, 45. 
car-box, 48. 
carmelia, 48. 
delta, 48. 
Ex. B., 48. 
graphite bearing, 48. 
gun, 45. 
magnolia, 48. 
Muntz, 45. 
salgee, 48. 
steam, 45. 

removwl, weight of, 477. 
white, 48. 
Metallurgical notes, 13. 
Metallurgy of iron 11. 

ores and their reduction, 1 1 . 
Meter, U. S. standard of length, 105. 
Micrometer calipers, 106. 
caliper square, 109. 
reauing, 108. 



Digitized by 



Google 



INDEX 



493 



Miller, umversal, 302. 

characteristic operations, 

275, 308. 
description of parts, 302. 
dividing head. 306. 
function and limitations, 

302. 
index drum. 308. 
raising block, 308. 
steadv rest and other at- 
tachments, 308. 
swivel vise, 308. 
tail stock, 308. 
Milling, chapter XIII, 298. 

assembling cutters, pollets and 

collars, 311. 
backing off drill lands, 327. 
bevel and miter gears, 323. 
boring and facing, 316. 
cutters, 338 to 345. 
9ee mills, 
a page of, 339. 
end slots, 311. 
face, 314. 

feeding and speeds, 311. 
feeds and speeds, 90, 91. 

fear cutting, 316. 
elical grooving, 325. 
bobbing a worm wheel, 322. 
influence of cutter diameters, 310. 
keyseating and fluting, 316. 
machine arbors, 337. 

horizontal, 298. 
ordinary types, 298. 
plain, 2f)8. 

universal, 302 to 309. 
vertical, 298. 
nomenclature, 310. 
order of operations, 312. 
preparation of work, 309. 
segment and spot finishing, 310. 
slot, 314. 
spiral. 319, 325. 
swivel vise adjustments, 312. 
terms and operations, 310. 
Mills, angular, 341. 

Doring and turning, 223. 

boring and turning, characteristic 

operations, 224. 
bonng and turning, description of 

parts, 223. 
boring and turning, function and 

limitations, 223. 
care of cutters and, 340. 
classification and design of cutters 

and, 338. 
cutting action of, 312. 
end, 342. 
face, 340. 
fly cutters, 342. 
form, 342. 
formed, 342. 
pang, 345. 
mserted tooth, 342. 
saws and Blotters, 344. 
side, 341. 
straddle, 314, 341, 345. 



Miscellaneous machine tools and acce»- 

sories, chapter XIV, 346. 
Miter gears, cutting, etc., 323. 
Mixtures, coating for laymg-out, 161. 
cutting, 58, 60, 201. 
heat mssipating, 60. 
marking tor scraping, 172. 
quenching bath, 365. 
soda water, 60. 
soft soap, 60. 
Modulus of elasticity, 20. 
Molybdenum, influence of, 17. 
Monitor lathes, 360. 
Morse tapers, 206. 

taper shanks, 252, 253. 
Motor, adjustable speed, 460. 
alternating current, 420. 
choice of, 465. 
compound, 463. 
constant speed, 458. 
driven boring mill, 222. 
driU, 240. 
lathe, 197. 
planer, 292. 

rotary, 301. 
drives, 453. 

advantages of, 453. 
cost of equipment, 453. 
economy of, 455. 
and motor driven machine 
tools, chapter XX, 453. 
reference to other data, 464. 
requiring adjustable speed 

service, 465. 
requiring compound service, 

465. 
requiring constant service, 

465. 
requiring variable service, 
465. 
electric, principles of, 418. 
equipments, horse-power for vari- 
ous machine tools, 477. 
gas, 386. 

horse-power consumption of, 456. 
hydraulic, 396. 
induction, 422. 
polyphase, 421. 
ratings, 469. 

for snop and machine tool driv- 
ing, 458. 
single phase, 416. 
speed regulation, electric, 420. 
synchronous, 421. 
variable speed. 460. 
variable speea, weights of, 470. 
working applications of, 465. 
Multiphase, see poIypha.se. 
Multiple arc circuits, 406. 
Muntz metal, 45. 
Mushet steel, 17, 34. 



N 



Naphtha engines, 393. 
Natural gas, see gas. 



Digitized by 



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494 



INDEX 



Nickel chrome steel, 29. 

influence of, 16. 

steel, 28. 
Non-corrosive metal, manganese bronze, 
47. 

expanding steel, (Invar), 34. 

magnetic steel, 30. 
Norway iron, manufacture of, 24. 
Numbered gages, 120. 

gages, criticism, 120. 
Nuts, 145. 

standard thread, bolt and nut data, 
148. 



Odontographies, laying-out gear teeth, 

331. 
Ohm, 404. 

Oil compounds and adulterations, 53. 
engines, the Diesel, 390. 

furls, 302, 394, 395. 
engine operation, 393. 
inspection, 56. 
tests, 55. 
Oiling, 4. 

Oils, acidity test, 55. 
animal, 54. 
chemical and physical properties 

of, 57. 
cold test, 55. 
composition of, 53. 
cylinder, 57. 

density and gravity test, 55. 
engine, 57. 
flash or fire test, 55. 
lubricating, 54. 
machinery, 57. 
marine, 58. 

objectionable features, 64. 
paraffine, 54. 
qualifications of a good lubricant, 

54. 
refrigerating, 58. 
specifications, 57. 
tempering, 3()5. 
tests. 55. 

for threading and tapping, 58, 104. 
vegetable, 54. 

vivscosity or fluidity test, 55. 
volatile, 56. 
wool fat, 54. 
Open hearth furnace, 13. 
steel, 27, 36. 
Operation, gas engine, 387. 
Operations, characteristic, borine mill. 
224. 
characteristic, lathes, 109. 
planer, 292. 
shaper, 288. 
universal grin<ling, 

269. 
\mivcTsal miller, 308. 
drilling, 237. 
in four cycle engines, 387. 
grinding," 258. 



Operations, hand abrasive, 270. 
lathe boring, 225. 
machine grmding, 270. 
milling defined, 310. 
order of, cylindrical and conical 

grinding, 275. 
order of, drilling, 245. 
grinding, 275. 
lathe boring, 227. 
mill boring, 227. 
milling, 312. 
planer, 297. 
screw cutting, 213. 
shaper, 296. 

for straight turning, 203. 
Order of operations, see operations. 
Orc»s, and their reduction, 11. 



Parafline, 54. 

Parallel circuits (multiple arc), 400* 

Parting tool, 97. 

Pearlite, softening carbon, 36. 

Pcening and hammering, 162. 

Pelt on water-wheel, 399. 

Petroleum engine, 390. 

fuel, 56, 392, 394. 
Pewter, 47. 

and ty|)e metal, 48. 
Phosphor bronze, 43, 45. 

bronze, drawn wire, 46. 
Phosj>horous, influence of, 14. 
Pliysical properties of alloys, 42. 

iron and steel, 

18. 
oil, 57. 
Pickling, cleaning castings and forgings. 

Pig iron, ba.sic, 21. 

Bessemer, 20. 

charcoal, 20. 
classification of commercial, 

20. 
Ferro-silicon, 21. 
foundr>', 20. 
gray forge, 21. 
Pinning, 204. 
Pins, (lowel and taper, 147. 

filing, 168. 
Pipe, hob, 138. 
reamer, 138. 
standard dimensions of wrought 

iron, 151. 
taps and dies, standard, 138. 
Pitch circular, 328. 
diameter, 327. 
diametral, 328. 
of milling cutters, 338. 
of screws, 135. 
.Mcrew gage, 124. 
Planer, b<»lt drive, 2<]0. 

characteristic operations, 292. 
description. 291. 
function and limitations, 290. 
jacks, 293. 



Digitized by 



Google 



INDEX 



495 



Planer, rotary, 301. 

rotary, motor driven, 301. 
spiral geared, 291. 
spur geared, motor driven, 292. 
tools, 100. 

diamond point, 101. 
discussion and theory, 100. 
roughing, 100.^ 
8haf)es and grinding of, 102. 
straight edge side, 101. 
with self-hardening steel 
cutters, 104. 
Planing, chapter XII, 285. 
accuracy and errors, 295. 
bevels or angles, 295. 
cuts terminating in a shoulder, 295. 
cutting speeds, 294. 
feeds and speeds, 93. 
machines, classes of, 285. 

kejrway cutter, 289. 
planer, 290. 

power required for, 478. 
shaper, 285. 
slotter, 289. 
order of operation for planer, 297. 
shaper, 2C6. 
practice, 294. 
preparation of work, 293. 
recesses and grooves, 295. 
undercuts and 1' slots, 295. 
Pneumatic hammers, 165. 
Polishing, 205. 
Polyphase motors, 421. 

motors, induction, 463. 
Power, 370. 

gases, commercial, 394. 

constituents of, 395. 
generating machines, chapter 

XVII, 376. 
graphs, indicator cards, 374. 
re<|uireiiients for reciprocating 

tools, 471. 
and steam computations, 374. 
transmission, chapter XIX, 415. 
Practice, drilling, 92. 
grinding, 274. 
milling, 90. 
planing, 93. 
turning, 89. 
Precision lathe, 190. 
Press fits, 178. 
Pres.ses, arbor, 347. 
assembling, 340. 
bench, 348. 
cla.s.sification, 340. 
die, 346, 349. 
dies for die, 350. 
hydraulic, 348. 
screw, 346. 
straightening, 348. 
Pressure factors, forcing fit, 187. 
Pressures, forcing fit, 179. 
Proces.ses, finishing, turning, 204. 
fitting, 176. 
laying out, 161. 

and manipulation, turning, 211. 
preparatory, turning, 201. 



Producer gas, 394. 
Propeller blade castings, 47. 
Protractor, bevel, 114. 
Puddled iron, 24. 

steel, 27. 
Puddling furnace, 13. 
Pulley lathe, 190. 
Pulleys, arrangement of, 444. 

crowning, 444. 

iron, steel and wood, 439, 441. 

mule, 446. 

rope transmission, 430, 441. 

tight and loose, 441. 
Punches, center, 131. 

pop, 131. 

pri^k, 131. 
Puncning presses, 346. 
Pyle, turbine, 378. 



Q 

Quartertwist belts, 445. 
Quenching batlis, 365. 



R 



Rack, involute laying out, 333. 

Radial drill, 342. 

Rake, angles of cutting tools, 61. 

negative, (52. 

sitlfc and top, 62. 
Ratinf2;s, motor, 469. 
Reaction wheels, 396, 399. 
Reamed holes, allowances for, 130. 
Reamer, arbors, 130. 

grinder, 261. 
Reamers 129. 

center, 252. 

cliucking, 233. 

fluted chucking, 236. 

pipe, 138. 

rosc^ chucking, 236. 

self feeding, 129. 

shell, 130. 

special drills and, 251. 

three and four fluted, 235. 
Recalescence or critical point, 37. 
Reciprocating tools, power retjuire- 

ments of, 471 . 
Record, exercise and time, 10. 

system for tool room, 7. 

tool and time, 8. 
Rectilinear work, laving out, 161. 
R.h1 brass, 46. * • 

hardness, 42. 

hardness, molybdenum, 17. 

shortness sulphur, 16. 
Reference ami test gages, 117. 
Refrigerating oils, .58. 
Revolutions, table of and cutting 

speeds, 88. 
Resi.stance, electrical of steel, 31. 
Rivets, 145. 
Ro<»blin^'s gage, 122. 
Rope drive for cotton mill, 426. 



Digitized by 



Google 



496 



INDEX 



Rope drives, continuous system, 428. 
multiple system, 427. 
vertical, continuous system, 
428. 

driving, 426. 

pulleys, 429. 

sheaves, 429. 

splicing, 432. 

transmission systems, 427. 

wire, transmission, 426. 
Rotary engine. Brotherhood, 385, 

planer, 298. 
Rotating field, induction motors, 422. 
Rotor, induction motors, 422. 
Roughing tool, lathe, 97. 

tool, planer, 100. 
Round-nose chisel, 94. 

nose graver, 95. 

lathe tool, 97. 
Rubber belting, 447. 
Rules, 105. 

for calculating gears, 327. 

relative to fe^ls and speeds, 63. 

for school shops, 9. 

for set over, taper turning, 206. 

shop, 2, 9. 

slide, 82. 

tool room for school shops, 7. 
Running fits, 184. 

fits, close allowances, 187. 
free allowances, 187. 
Rust joints, 369. 



S 

Salgee anti-friction metal, 48. 
Sand bath, tempering, 366. 
Sawing, hack, 163. 
Saws, hack, 163. 

slitting and slotting, 344. 
Scrapers, 95. 
flat, 96. 

three-cornered, 96. 
Scraping edge drill, 249. 
m the lathe, 173. 
lathe work, 205. 
a plane surface, 171. 
use of turpentine in, 173. 
Screw arbors, milling, 337. 
cutting, 208. 

catching threads, 21 1 . 
metric threads, 214. 
notes on, 214. 
order of operations for, 

213. 
process and manipulation, 

211. 
use of center gage, 125. 
gage, American, 122. 

wood and machine, 123. 
machines, 359. 
parts, lead, 135. 

nomenclature, 135. 
pitch, 135. 

threads per inch, 135. 
turns to an inch, 135. 



Screw and pin data, chapter VI, 
135. 
pitch gage. 124. 
plates or aies, 137. 
Blotters, 344. 

thread 29° Acme standard, 217. 
table of parts, 218. 
Screws, cap, 140. 
coach, 142. 
hanger, 142. 
lag, 142. 
machine, 138. 

A.S.M.E. standard pro- 
portions, 155. 
proportions, old style, 

set, 140. 

standard cap, tabulated data, 153. 
set, tabulated data, 153. 

wood, 138. 
Scribcrs, 131. 
Segment finishing, 316. 
Self-hardening steel, 17, 31,34. 

annealing, 32. 
tool holders, lathe, 
103. 
planer, 
104. 
Sensitive friction drill, 238 
Series circuits, 406. 

wound dynamos or generators, 414. 
motors, 461. 
Set screws, 140. 

screws standard tabulated data, 
153. 
Shafting, 436. 

arrangement of, 444. 

bearings and hangers, 439. 

countershaft, 437. 

deflection of, 438. 

jack, 437. 

line, 437. 

lining up, 447. 

speed of, 438. 

strength of, 437. 

supports, 438. 
Shanks, arbor, 206, 337. 

drill, 206, 252. 

Morse taper, 206, 253. 
Shape of tool, 62. 
Shaper, characteristic operations, 288. 

crank, 287. 

description of, 285. 

functions and limitations, 285. 

geared, 286. 
Shearing strength of standard U. S. 

bolts, 148. 
Sheaves, rope tran.smission, 430. 
Sheet metal and wire gages compared, 

122. 
Shell end mills, 342. 

mill arbors, 337. 
Shims or liners for broaching, 176. 
Shop, carefulness in the, 3. 

equipment, 6. 

ethics, 2. 

order in the, 2, 5. 



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Google 



INDEX 



497 



Shop, processes and kinks, chapter XV, 
365. 

regulation, 0. 

rules, 2. 

tool room, 6. 
Shrinking fit allowances, 187. 

fits, 182. 
Shunt wound, constant speed motors, 
459, 460. 

wound dvnamos or generators, 414. 
Side milling, 314. 

cutters, 341. 

cutter, action of, 312, 341. 

tools, lathe, 97. 

tool, straight edge, planer, 101. 
Siderite. 11. 
Silicon oronse, 46. 

influence of, 16. 

steel, 31. 
Silver, German solder, 47. 

solder, 47. 
Single-phase motors, 416, 461. 
Sixty degree or V thread, 216. 
Slitting saws, 344. 
Slots, dovetail, 317. 

end milling, 311. 

milling, 314. 

cutters for, 342. 

planing T 2: 5. 
Slottera, description, 289. 

screw (milling), 344. 
Slotter tools, 102, 2<;0. 
Small tools, 127. 

arbors or mandrels, 127. 

calipers, 130. 

center punches, 131. 

dividers, 131. 

reamers, 129. 

scribers, 131. 

wrenches, 134. 
Snap gages, 118. 
Soapstone, see talc. 
Sockets or collets for milling arbors, 338. 

drill, 254. 
Soda water, 60. 
Solders, 46. 

Brazing, 45. 

common, 46. 

German silver, 47. 

gold, 47. 

IKJwter, 47. 

silver, 47. 
Soldering, terms, 368. 
Solenoids, strength of, 408. 
Speed, adjustable motors, 460. 
service, 465. 

compound service, 465. 

constant, motors, 458. 
service, 465. 

control for motors. 467. 

relations for motors, 468. 
svstems and wiring, 468. 

of drills, 246. 

or hand lathe, IfO. 

effect of cut and feed on, 81. 

effect of texture on, 84. 

ranges, motor, 466. 



Speed, regulation, electric, 466. 
motor, 420. 
of shafting, 438. 
torc^ue curves, 462. 
variable service, 465. 

speed motors, 460. 
Speeds, of abrasive wheels, 277. 
cutting for drilling, 92. 
for drills, 246. 
for files, 205. 
for grinding, 272. 
for milling, 90, 91. 
for planing, 93. 
power required for, 477. 
tor turning, 70, 89. 
and feeds, see feeds and speeds, 
of gear teeth, 335. 
Spiegeleisen, 27. 
Spiral geared planer^ 291. 

grooving and milling, 325. 
Splicmg, transmission rope, 432. 

transmission rope, data relative to, 
430. 
Spot facing, 237. 

finislung, 316. 
Square holes, forging, 369. 
micrometer caliper, 109. 
thread, 215. 
try, 106. 
Stamping presses, 346. 
Standard dimensions of wrought iron 
pipe, 151. 
key-seats, table of, 175. 
machine screw pro[X)rtions, old 

style, 154. 
machine screw proportions, A.S. 

M.E., 155. 
of measurement, historical, 105. 
pipe taps and dies, 138. 
set and cap screws, 153. 
taps, 136. 
thread bolt and nut data, U. S., 

148. 
thread proportions, 215. 
U. S. gage, 121, 122, 
U. S. thread, 215. 
yard, 105. 
StanHards, electricity, 403. 

of measurement, meter, 105. 
Stator, induction motors, 423. 
Steam, action of in Del^aval turbine, 
379. 
and coal consumption, table of 

comparative, 385. 
engine. 376. 

flow ot in Curtis turbine, 383. 
metal, 45. 

and power computations, 374. 
turbine, 378. 

Curtis, 381. 
DeLaval, 379. 
Dow 378. 
Pyle, 378. 

West inghouso-Parsoiis, 
383. 
Steel, alloy, aluminum, 33. 
cobalt, 33. 



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498 



INDEX 



Steel, alloy, and high speed, 34. 
tin, 33. 
titanium, 33. 

alloys, 28. 

and iron coloring, 366. 
working, 365. 

annealing, self-hardening, 32. 

armor plate, 28. 

Bessemer, 26. 

blister, 26. 

carbon, 14, 27. 

carbon content of iron and, 19. 

case-hardening iron and, 366. 

castings, 35. 

chrome, 28. 

classification of. 25. 

comparison witn cast and wrought 
iron, 23. 

conductivity of iron and, 20. 

converted or cemented, 25. 

cooling and heating curves, 38, 39. 

crucible cast, 26. 

Damascus, 32. 

German, 26. 

hardening and tempering, 40. 

hard, horae-power required for cut- 
ting, 473. 

high speed cutting on cast iron, 82. 
recent practice, 
89. 

Invar, non^^xpanding, 34. 

low speed, investigation, 64. 

manganese, 30. 

metfdlurgical notes, 13. 

metalluivy of, 11. 

nickel, 28: 

nickel-chrome, 29. 

non-corrodible, 28. 

non-expanding. Invar, 34. 

non-magnetic, 28, 30. 

open hearth and puddled, 27. 

physical properties, 18. 

recalescent point, 37. 

resista, 34. 

shear, 26. 

silicon, 31. 

soft, horse-power required for cut- 
ting, 475. 

structural, 16, 36. 

structure of, 35. 

Taylor-White treatment of, 42. 

temi.ering data, 40. 

theory of hardening, 36. 

tool or carbon, 14, 27. 

and its treatment, 81. 

treatment of. 35. 

tungsten or Mushet, 17, 31, 34. 

vanadium and vanadium-chrome, 
32. 

working, 36. 
Stove bolts, 145. 

plate iron, 21. 
Straddle mills, 341, 345. 
Straight edge, 1 13. 

edge side tool, planer, 101. 

fluted drill, 250. 
Strength of alloys, 43, 46. 



Strength of cutting edge, 61. 

of electro magnets, 408. 

of gear teeth, 335. 

of shafting, 437. 

of solenoids, 408. 

shearing for standard bolts, 148. 

tensile for standard bolts, 148. 
Stub's or Birmingham wire gage, 121. 

iron wire gage, 122. 
Structural ste^, 16, 36. 
Studs, 145. 

Sulphur, influence of, 16. 
Sunace gage, universal, 126. 

gage, universal methods of using, 
128. 

plate, scraping a, 172. 
Surfacing, hand, 270. 
Sweating, 368. 

Symbols, electrical, 403, 404. 
Synchronous motors, 421. 
System, check, 7. 

record, 7. 
Systems, electric transmission, alternat- 
ing current, 416. 

electric transmission continuous 
current, 416. 

electric transmission, efficiency of, 
415. 

governing conditions, 415. 

methods of, 416. 

motor dynamo, 417. 

multiple phase, 417. 

multiple wire, 417. 

regenerating, 417. 

single {)ha8e, 417. 

three wire, 417. 

two wire^ 417. 

of electncal distribution, 417. 

of rope transmission, 427. 

tool room, 6. 

and wiring, 468. 



Talc, 60, 276. 
Taper pms, 147. 
turning, 205. 

attachment, 199. 
rule for set-over, 206. 
theoretical height of tool, 
207. 
Tapers and angles, table of, 116. 
Brown and Sharpe, 206. 
methods of tunung, 205. 
Morse, 206, 253. 
Morse taper shanks, 253. 
Tap drills for machine screws, 137. 149. 
for machine screws, A.S.M.E., 

150. 
for pipe taps, 151. 
for set and cap screws, 153. 
for standard bolts, 148. 
and thread data for machine 
screws, old style, 149. 
Tapping, 164. 
chucks, 256. 



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Google 



INDEX 



499 



Tapping, depth of tapped holes, 165. 
TApB. aligning, 164. 
bottoming, 136. 
and dies, standard pipe, 138. 
hand, 136. 
machine screw, 136. 
pipe, 138. 
plug, 136. 
standard, 136. 

thread bolt and nut data, 
148. 
taper 136. 
Taylor, The art of cutting metals, ab- 
stract of, 72. 
-White process, 17. 
-White treatment of tool steels, 42. 
Teeth, gear, cycloidal, 331. 
gear, horse-power, 335. 
internal, 333. 
involute, 332. 
odontographies, laying out, 

331. 
speed of, 335. 
strength of, 335. 
table of cycloidal, 332. 
involute, 334. 
tooth parts, 330. 
mill, inserted cutters, 344. 
Tempering, air, 365. 
colors, 41. 
data, 41. 

hardening and, 40. 
oil, etc., 365. 
theory of, 36. 
Templets, 364. 
Tensile strength of standard U. S. bolts, 

148. 
Test and reference gages, 117. 
Tests, acidity, 55. 
cold, 55. 

density or gravity, 55. 
flash or fire, 55. 
oil, 55. 

oil inspection. 56. 
viscosity or fluidity, 55. 
Thermal unit, British, 371, 395. 
Theory, cutting tools, 61. 

and discussion, turbines, 396. 
heat. 371. 

height of tool taper, turning, 207. 
planer tools, 100. 
square thread cutting, 215. 
and thermodynamics, 386. 
Thermodynamics,* Beau de Rochas con- 
clusions, 386. 
an experiment in, 372. 
indicator cards, 373. 
Otto and Clerk cycles, 386. 
power and steam computation, 374. 
table of comparative steam and 

coal consumption, 385. 
and theory, 386. 
Thread, B. & S. twenty-nine degree 
worm, 217. 
British standard or Whitworth, 

218. 
proportions, 215. 



Thread, sixty degree V., 216. 
square, 215. 
and tap data for machine screws, 

A. S. M. E. standard, 150. 
and tap data for machine screws, 

old style standard, 149. 
trapezoidal, 219. 
twenty-nine degree screw, acme 

standard, 217. 
twenty-nine degree screw thread 

parts, 218. 
B. & S. twenty-nine degree worm 

thread, 217. 
U. S. Standard, 148, 215. 
Threads, double, 214. 
per inch, 135. 
left-hand, 214. 
machine screw, 149, 150. 
metric screw, 214. 
standard, 148, 215. 

bolt and nut data, 148. 
Threading, 163. 

see screw cutting, 
tool, 98, 208. 

adjusting the, 213. 
method of setting, 125. 
U. S. standard, 98. 
Time record, tool and, 8. 

record school shops, 10. 
Tin-copper alloys, 43. 

copper-zinc alloys, 43. 
influence of, 18. 
pure Banca, 49. 
steel, 33. 
Titanium, influence of, 18. 

steel, 33. 
Tobin bronze, 45, 48. 
Tool holders, 103. 

maker's lathe, 188. 
room, 6. 

check system, 7. 
record system, 7. 
rules, 7. 
shape of, 62. 
steel, 27. 

chemical analvsis of, 27. 
cooling and heating curves, 

38, 39. 
high speed cutting, analysis 

of, 34. 
high speed, Taylor's investi- 
gations, 72. 
Taylor-White treatment of, 
42. 
and time record, 8. 
Tools, box and turners, 352 to 359. 
broaching, 176. 

chucks and boring, 231 to 236. 
8ee cutting. 

cutting, durability of edge, 61. 
feeds an(i speeds, 62. 
governing con<iitions, 61. 
height of, in taper turn- 
ing, 207. 
strength of edge, 61. 
filing, 168. 
hand, 93. 



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500 



INDEX 



Tools, high speed, cutting on cast iron, 
82. 
investigations, 72. 
recent practice, 89. 
horse-power requirements of re- 
ciprocating, 471. 
keenness of, 61. 
lathe, 97. 

low speed investigation of, 64. 
machme, horse-power of motor 

eouipments for. 478. 
macnine motors lor, 458. 
planer, 100. 

relative positions of work and, 61 . 
requiring compound motor service, 

slotter, 102. 
and work, 5. 
Torque, speed curves, induction motor. 

Transmission, belt, 447. 

compressed air, 423. 

data electric, 416. 

electric, 416. 

governing conditions, 415. 
methods of, 416, 417. 

horse-power of belting, 451. 

hydraulic, 425. 

pulley, 436. 

rope, 431. 

shaft, 436. 

wire rope, 426. 
Trapezoidal thread, 219. 
Trenton Iron Go's wire gage, 122. 
Try square, 106. 
Tungsten, influence of, 17. 

or Mushet steel, 31, 34. 
Turbine wheels, 399. 
Turbines, 378. 

action of steam in DeLaval, 370. 

classes and uses, hydraulic, 3i>8. 

Curtis, 381. 

DeLaval, 379. 

Doble (water), 399. 

Dow, 378. 

ellipsoidal buckets, 400. 

flow of steam in Curtis, 381, 383. 

impulse wheels, hydraulic, 399. 

Pelton (water), 399. 

Pyle, 378. 

reaction wheels, hydraulic, 399. 

regulating nozzle, 400. 

steam, 378. 

table of comparative steam and 
coal consimiption, 385. 

theory, 378. 

theory and discussion, hydraulic, 
396. 

WcHtinghouse-Parsons, 383. 
Tumbuckles, 147. 
Turners and box tools, 351. 

illustrations of 14, 352 to 369. 
Turning, chapter VIII, 188. 

and boring mills, 223. 

feeds and speeds, 89. 

filing, 204. 

machines, 188. 



Turning, machines, power required for, 
478. 

manipulation, 202. 

order of operations, 203. 

p)oli8hing, 205. 

precautions, 63. 

scraping, 205. 

taper, 206. 

height of tool, 207. 
Turns to an inch, 136. 
Turret lathe, 190, 350. 

machines, 350. 

tools, 352 to 358. 
Twenty-nine degree screw thread, acme 
standard, 217. 

nine degree screw thread parts,218. 
worm thread, 217. 
Twist drill, 250. 

drill, milling a, 327. 

drill and steel wire gage, 122. 
Type metal, 48. 



U 



Unit, electrical, 403. 

of heat, British thermal unit, 371, 
395. 
United States box metal, 46. 
nav^' composition alloy, 45. 
standard gage, 121. 

gage for sheet and plate 

iron, 122. 
thread, 215. 

thread bolt and nut data, 
148. 
Universal surface gage, 126. 
chucks, 229. 

cutter and reamer grinder, 261. 
disc grinder, 260. 
grincier, characteristic operations, 

269. 
grinder, description of parts, 267. 
function and lunitations, 
264. 
miller, 302. 

dividing head, 306. 
milling machines, 302. 
and radial drills, 242. 
Upright drill, 239. 



Vanadium, influence of, 17. 

chrome steel, 32. 

steel, 32. 
Variable speed motors, 460. 

speed motors, weights of, 470. 
service for motors, 465. 
Vegetable oils, 54. 
Vernier calipers, 112. 

reading, 111. 

and its u.<ie, 111. 
Viscositv test for oils, 55. 
Vise, drill, 245. 

machinist's bench, 6. 



Digitized by 



Google 



INDEX 



501 



Vise, planer, 296, 297. 

swivel, adivistments, 312. 

swivel, milling, 308. 
Volatile oils, 56. 
Volt 404. 
"V^ or 60** thread, 216. 



W 

Washburn and Moen Go's gage, 121, 

122. 
Washers, 145. 

Water, analo^es between flow of and 
electricity, 404. 
annealing, 365. 
cut, 60, 372. 
gas, 394. 
wheels, 396. 

American, 402. 
breast, 3L6. 
Boyden, 402. 
Doble. 399, 400. 
Girard, 399. 
Leffel, 401. 
overshot, 396. 
Pelton, 31)9. 
Risdon, 402. 
Swain, 402. 
undershot, 396. 
Watt, 370, 403. 

kilowatt, 370. 
Weight of metal removed, 477. 
of metal removed, drilling, 92. 

milling, 90, 92. 
planing, 93. 
turning, 90. 
Westinghouse-Parsons turbine, 383. 

Parsons turbine generator sets, 
385. 
Wet grinder, 260. 

service oils, 58. 
Wheel, car iron, 21 . 

bobbing a worm, 322. 
lathe, 190. 
Wheels, abrasive or grinding, 277. 
^ar, rules for, 328. 
impulse, 399. 
reaction, 399. 

sizing and cutting of gear, 327. 
water, 306. 
Whistles, bronze for, 46. 
White metal, 48. 

-Taylor, see Taylor-White. 
Whitworth or British standard thread, 

218. 
Windings, 413. 

compound, 414. 
separately excited, 414. 
series, 414. 
slumt, 414. 
Wire, British imperial standard gage, 
122. 
copper, 46. 

gage twist drill and st^el wire, 124. 
multiple voltage system, '469. 
phosphor bronze, 46. 



Wire, relative conductivity of, 46. 

required for electric transmission, 

416. 
rope transmission, 426. 
and sheet metal gages compared, 

122. 
silicon bronze, 46. 
Stubs' or Birmingham gage, 121. 
Stubs' iron gage, 122. 
telephone and telegraph, 46. 
three, system, 469. 
Trenton Iron Cki's gage, 122. 
two, system, 469. 
Wiring systems, 468. 
Wood screws, 138. 
Wool fat (degras), 54. 
Work, 370. 

adjusting lathe, 203. 

for milling operations, 

312. 
for planer, 297. 
adjustment or, in boring mill, 227. 
of, in carriage, 227. 
of, in chuck, 226. 
of, in face plate, 227. 
bench and vise, laying out, 161. 
chipping, preparation for, 166. 
examples of milling, 314. 
forming lathe. 363. 
laying out cvlindrical, 161. 
driU, 162. 
rectilinear, 161. 
preparation of, for boring, 225. 
of, for drilling, 244. 
of, for grinding, 270. 
of, for milling, 309. 
of, for planing, 293. 
of, for turning, 201 . 
relation between heat and, 371. 
shaper, 296. 
Working iron and steel, 365. 
steel, 36. 

annealing, 12. 22, 365. 

self-hardening, 32. 
Iiardening and tempering, 36 

to 42. 
treatment of, 35. 
Worm thread, B. & S. 29°, 217. 

wheel, bobbing a, 322. 
Wrenches^ 134. 
Wrought iron, 19. 

case-hardening, 23, 366. 

charcoal, 24. 
commercial designation of, 25. 
comparison with cast iron and steel, 

23. 
composition of, 24. 
fagot, 24. 
Norway, 24. 

pipe, standard dimensions of, 151. 
power required for cutting, 474. 
properties of, 25. 
puddle<l, 24. 
pure chemical, 24. 
working, 25. 



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502 



INDEX 



Yard, bronze No. 1, 106. 
No. 11, 105. 
Low Moor iron No. 67, 106. 
8tand|uxl imperial, 105. 



Zino-chloride quenching bath, 365. 
-copper-tin alloys, 43, 
-copper alloys, 43. 



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